# Proto-Indo-European language

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Ancestor of the Indo-European languages

"PIE" and "Proto-Indo-European" redirect here. For the people, see [Proto-Indo-Europeans](/source/Proto-Indo-Europeans). For other uses, see [PIE (disambiguation)](/source/PIE_(disambiguation)).

Not to be confused with [Pre-Indo-European languages](/source/Pre-Indo-European_languages) or [Paleo-European languages](/source/Paleo-European_languages).

Proto-Indo-European PIE Reconstruction of Indo-European languages Region Proto-Indo-European homeland, most likely on the Pontic–Caspian steppe Era c. 4500 – c. 2500 BC Lower-order reconstructions Proto-Albanian Proto-Anatolian Proto-Armenian Proto-Balto-Slavic Proto-Celtic Proto-Germanic Proto-Greek Proto-Indo-Iranian Proto-Italic Proto-Tocharian

**This article contains characters used to write reconstructed Proto-Indo-European words (for an explanation of the notation, see [Proto-Indo-European phonology](/source/Proto-Indo-European_phonology)).** Without proper [rendering support](https://en.wikipedia.org/wiki/Help:Special_characters), you may see [question marks, boxes, or other symbols](/source/Specials_(Unicode_block)#Replacement_character) instead of [Unicode](/source/Unicode) combining characters and [Latin](/source/Latin_script) characters.

**Proto-Indo-European** (**PIE**) is the reconstructed common ancestor of the [Indo-European language family](/source/Indo-European_language_family).[1] No direct record of Proto-Indo-European has been discovered; its proposed features have been derived by [linguistic reconstruction](/source/Linguistic_reconstruction) from documented Indo-European languages. Far more work has gone into reconstructing PIE than any other [proto-language](/source/Proto-language). The majority of linguistic work during the 19th century was devoted to the reconstruction of PIE and its [daughter languages](/source/Daughter_language), and many of the modern techniques of linguistic reconstruction (such as the [comparative method](/source/Comparative_method)) were developed as a result.[2]

PIE is hypothesized to have been spoken as a single language from approximately 4500 BCE to 2500 BCE[3] during the Late [Neolithic](/source/Neolithic) to Early [Bronze Age](/source/Bronze_Age), though other estimates place the bounds of the period as much as more than a thousand years later. According to the prevailing [Kurgan hypothesis](/source/Kurgan_hypothesis), the [original homeland](/source/Proto-Indo-European_homeland) of the [Proto-Indo-Europeans](/source/Proto-Indo-Europeans) may have been in the [Pontic–Caspian steppe](/source/Pontic%E2%80%93Caspian_steppe) of eastern Europe and central Asia. The linguistic reconstruction of PIE has provided insight into the pastoral [culture](/source/Proto-Indo-European_culture) and patriarchal [religion](/source/Proto-Indo-European_religion) of its speakers.[4]: 16 As speakers of Proto-Indo-European became isolated from each other through the [Indo-European migrations](/source/Indo-European_migrations), the regional [dialects](/source/Dialect) of Proto-Indo-European spoken by the various groups diverged, as each dialect [underwent shifts in pronunciation](/source/Indo-European_sound_laws), [morphology](/source/Morphology_(linguistics)), and vocabulary. Over many centuries, these dialects transformed into the known ancient Indo-European languages. From there, more linguistic divergence led to the evolution of their current descendants, the modern Indo-European languages.

PIE is believed to have had an elaborate system of morphology that included [inflectional suffixes](/source/Inflection) (analogous to English *child, child's, children, children's*) as well as [ablaut](/source/Indo-European_ablaut) (vowel alterations, as preserved in English *sing, sang, sung, song*) and [accent](/source/Proto-Indo-European_accent). PIE [nominals](/source/Proto-Indo-European_nominals) and [pronouns](/source/Proto-Indo-European_pronouns) had a complex system of [declension](/source/Declension), and [verbs](/source/Proto-Indo-European_verbs) similarly had a complex system of [conjugation](/source/Grammatical_conjugation). The PIE [phonology](/source/Proto-Indo-European_phonology), [particles](/source/Proto-Indo-European_particles), [numerals](/source/Proto-Indo-European_numerals), and [copula](/source/Indo-European_copula) are also well-reconstructed. Asterisks are used by linguists as a conventional mark of reconstructed words, such as **wódr̥*, **ḱwn̥tós*, or **tréyes*; these forms are the reconstructed ancestors of the modern English words *water*, *hound*, and *three*, respectively.

## Development of the hypothesis

Part of a series on Indo-European topics Languages List of Indo-European languages Extant Albanoid Albanian Armenian Balto-Slavic Baltic Slavic Celtic Germanic Hellenic Greek Indo-Iranian Indo-Aryan Iranian Nuristani Italic Romance Extinct Anatolian Tocharian Paleo-Balkan Dacian Illyrian Liburnian Messapic Mysian Paeonian Phrygian Thracian Reconstructed Proto-Indo-European language Phonology: Sound laws, Accent, Ablaut Hypothetical Balkanic Daco-Thracian Graeco-Albanian Graeco-Armenian Graeco-Aryan Graeco-Phrygian Indo-Hittite Italo-Celtic Thraco-Illyrian Grammar Vocabulary Root Verbs Nouns Pronouns Numerals Particles Other Proto-Albanian Proto-Anatolian Proto-Armenian Proto-Germanic (Proto-Norse) Proto-Italo-Celtic (Proto-Celtic · Proto-Italic) Proto-Greek Proto-Balto-Slavic (Proto-Slavic · Proto-Baltic) Proto-Indo-Iranian (Proto-Indo-Aryan, Proto-Iranian, Proto-Nuristani) Philology Anitta text Hittite inscriptions Hieroglyphic Luwian Linear B Rigveda Avesta Homer Behistun Greek epigraphy Phrygian epigraphy Messapic epigraphy Latin epigraphy Gaulish epigraphy Runic epigraphy Ogham Gothic Bible Bible translations into Armenian Tocharian script Old Irish glosses Albanian Kanun Origins Homeland Proto-Indo-Europeans Society Religion Mainstream Kurgan hypothesis Indo-European migrations Eurasian nomads Alternative and fringe Anatolian hypothesis Armenian hypothesis Beech argument Indigenous Aryanism Baltic homeland Paleolithic continuity theory Archaeology Chalcolithic (Copper Age) Pontic Steppe Domestication of the horse Kurgan Kurgan stelae Kurgan culture Steppe cultures Bug–Dniester Sredny Stog Dnieper–Donets Samara Khvalynsk Yamnaya Mikhailovka culture Novotitarovskaya culture Caucasus Maykop East Asia Afanasievo Eastern Europe Usatove Cernavodă Cucuteni Northern Europe Corded ware Baden Middle Dnieper Bronze Age Pontic Steppe Chariot Yamnaya Catacomb Multi-cordoned ware Poltavka Srubnaya Northern/Eastern Steppe Abashevo culture Andronovo Sintashta Europe Globular Amphora Corded ware Bell Beaker Únětice Trzciniec Nordic Bronze Age Terramare Tumulus Urnfield Proto-Villanovan Lusatian Este South Asia Bishkent Vakhsh BMAC Ochre Coloured Pottery Copper Hoard Cemetery H Gandhara grave Iron Age Steppe Chernoles Europe Thraco-Cimmerian Hallstatt Latial Jastorf Caucasus Colchian Central Asia Yaz India Painted Grey Ware Northern Black Polished Ware Peoples and societies Bronze Age Anatolian peoples (Hittites) Armenians Mycenaean Greeks Indo-Iranians Iron Age Indo-Aryans Indo-Aryans Iranians Iranians Nuristanis Nuristanis East Asia Wusun Yuezhi Europe Celts Gauls Celtiberians Insular Celts Cimmerians Hellenic peoples Italic peoples Germanic peoples Paleo-Balkan/Anatolia Thracians Dacians Illyrians Paeonians Phrygians Scythians Middle Ages East Asia Tocharians Europe Albanians Balts Slavs Norsemen/Medieval Scandinavians Middle Ages Indo-Aryan Medieval India Iranian Greater Iran Religion and mythology Reconstructed Proto-Indo-European mythology Proto-Indo-Iranian religion Historical Vedic religion Ancient Iranian religion Historical Hittite Indo-Aryan Vedic Hinduism Buddhism Jainism Sikhism Iranian Persian Zoroastrianism Kurdish Yazidism Yarsanism Scythian Ossetian Others Armenian European Paleo-Balkan (Albanian · Illyrian · Thracian · Dacian) Greek Roman Celtic Irish Scottish Breton Welsh Cornish Germanic Anglo-Saxon Continental Norse Baltic Latvian Lithuanian Slavic Practices Fire rituals Horse sacrifice Sati Winter solstice/Yule Indo-European studies Scholars Marija Gimbutas J. P. Mallory Institutes Copenhagen Studies in Indo-European Publications Encyclopedia of Indo-European Culture The Horse, the Wheel, and Language Journal of Indo-European Studies Indogermanisches etymologisches Wörterbuch Indo-European Etymological Dictionary Category v t e

No direct evidence of the Proto-Indo-European language exists; scholars have reconstructed PIE from its present-day descendants using the [comparative method](/source/Comparative_method_(linguistics)).[5] For example, compare the pairs of words in Italian and English: *piede* and *foot*, *padre* and *father*, *pesce* and *fish*. Since there is a consistent correspondence of the initial consonants (*p* and *f*) that emerges far too frequently to be unrelated coincidence, one can infer that these languages stem from a common [parent language](/source/Parent_language).[6] Detailed analysis suggests a system of [sound laws](/source/Indo-European_sound_laws) to describe the [phonetic](/source/Phonetics) and [phonological](/source/Phonology) changes from the hypothetical ancestral words to the modern ones. These laws have become so detailed and reliable as to support the [Neogrammarian hypothesis](/source/Neogrammarian_hypothesis): the Indo-European sound laws apply without exception.

[William Jones](/source/William_Jones_(philologist)), an [Anglo-Welsh](/source/Anglo-Welsh) [philologist](/source/Philology) and [puisne judge](/source/Puisne_judge) in [Bengal](/source/Bengal), caused an academic sensation when in 1786 he postulated the common ancestry of [Sanskrit](/source/Sanskrit), [Greek](/source/Greek_language), [Latin](/source/Latin), [Gothic](/source/Gothic_language), the [Celtic languages](/source/Celtic_languages), and [Old Persian](/source/Old_Persian),[7] but he was not the first to state such a hypothesis. In the 16th century, European visitors to the [Indian subcontinent](/source/Indian_subcontinent) became aware of similarities between [Indo-Iranian languages](/source/Indo-Iranian_language) and European languages,[8] and as early as 1653, [Marcus Zuerius van Boxhorn](/source/Marcus_Zuerius_van_Boxhorn) had published a proposal for a [proto-language](/source/Proto-language) ("Scythian") for the following language families: [Germanic](/source/Germanic_languages), [Romance](/source/Romance_languages), [Greek](/source/Hellenic_languages), [Baltic](/source/Baltic_languages), [Slavic](/source/Slavic_languages), [Celtic](/source/Celtic_languages), and [Iranian](/source/Iranian_languages).[9] In a memoir sent to the [Académie des Inscriptions et Belles-Lettres](/source/Acad%C3%A9mie_des_Inscriptions_et_Belles-Lettres) in 1767, [Gaston-Laurent Coeurdoux](/source/Gaston-Laurent_Coeurdoux), a French [Jesuit](/source/Jesuit) who spent most of his life in India, had specifically demonstrated the analogy between Sanskrit and European languages.[10] According to current academic consensus, Jones's famous work of 1786 was less accurate than his predecessors', as he erroneously included [Egyptian](/source/Egyptian_language), [Japanese](/source/Japanese_language) and [Chinese](/source/Chinese_language) in the Indo-European languages, while omitting [Hindi](/source/Hindi).

In 1818, Danish linguist [Rasmus Christian Rask](/source/Rasmus_Christian_Rask) elaborated the set of correspondences in his prize essay *Undersøgelse om det gamle Nordiske eller Islandske Sprogs Oprindelse* ('Investigation of the Origin of the Old Norse or Icelandic Language'), where he argued that [Old Norse](/source/Old_Norse) was related to the Germanic languages, and even suggested a relation to the Baltic, Slavic, Greek, Latin and Romance languages.[11] In 1816, [Franz Bopp](/source/Franz_Bopp) published *On the System of Conjugation in Sanskrit*, in which he investigated the common origin of Sanskrit, Persian, Greek, Latin, and German. In 1833, he began publishing the *Comparative Grammar of Sanskrit, [Zend](/source/Avestan), Greek, Latin, Lithuanian, Old Slavic, Gothic, and German*.[12]

In 1822, [Jacob Grimm](/source/Jacob_Grimm) formulated what became known as [Grimm's law](/source/Grimm's_law) as a general rule in his *Deutsche Grammatik*. Grimm showed correlations between the Germanic and other Indo-European languages and demonstrated that sound change systematically transforms all words of a language.[13] From the 1870s, the Neogrammarians proposed that sound laws have no exceptions, as illustrated by [Verner's law](/source/Verner's_law), published in 1876, which resolved apparent exceptions to Grimm's law by exploring the role of accent (stress) in language change.[14]

[August Schleicher](/source/August_Schleicher)'s *A Compendium of the Comparative Grammar of the Indo-European, Sanskrit, Greek and Latin Languages* (1874–77) represented an early attempt to reconstruct the Proto-Indo-European language.[15]

By the early 1900s, [Indo-Europeanists](/source/Indo-Europeanist) had developed well-defined descriptions of PIE which scholars still accept today. Later, the discovery of the [Anatolian](/source/Anatolian_languages) and [Tocharian languages](/source/Tocharian_languages) added to the corpus of descendant languages. A subtle new principle won wide acceptance: the [laryngeal theory](/source/Laryngeal_theory), which explained irregularities in the reconstruction of Proto-Indo-European phonology as the effects of hypothetical sounds which no longer exist in all languages documented prior to the excavation of [cuneiform](/source/Cuneiform) tablets in Anatolian. This theory was first proposed by [Ferdinand de Saussure](/source/Ferdinand_de_Saussure) in 1879 on the basis of internal reconstruction only,[16] and progressively won general acceptance after [Jerzy Kuryłowicz](/source/Jerzy_Kury%C5%82owicz)'s discovery of consonantal reflexes of these reconstructed sounds in Hittite.[17]

[Julius Pokorny](/source/Julius_Pokorny)'s *[Indogermanisches etymologisches Wörterbuch](/source/Indogermanisches_etymologisches_W%C3%B6rterbuch)* ('Indo-European Etymological Dictionary', 1959) gave a detailed, though conservative, overview of the lexical knowledge accumulated by 1959. Jerzy Kuryłowicz's 1956 *Apophonie* gave a better understanding of [Indo-European ablaut](/source/Indo-European_ablaut). From the 1960s, knowledge of Anatolian became robust enough to establish its relationship to PIE.

In *The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World*, Mallory and Adams illustrate the resemblance with the following examples of [cognate](/source/Cognate) forms (with the addition of Old English for further comparison):[18]: 3, 5, 135, 209–210

- Examples of cognate words in Indo-European languages PIE Modern English Old English Latin Greek Sanskrit *méh₂tēr mother mōdor māter mḗtēr mātár- *ph₂tḗr father fæder pater patḗr pitár- *bʰréh₂tēr brother brōþor frāter phrḗtēr bhrā́tar- *swésōr sister sweostor soror éor svásar- *suHnús, *suHyús son sunu — huiús sūnú- *dʰugh₂tḗr daughter dohtor — thugátēr duhitár- *gʷṓus cow cū bōs boûs gáu-

## Historical and geographical setting

Main article: [Proto-Indo-European homeland](/source/Proto-Indo-European_homeland)

Early [Indo-European migrations](/source/Indo-European_migrations) from the [Pontic steppes](/source/Pontic_steppes) and across Central Asia according to the widely held Kurgan hypothesis

Scholars have proposed multiple hypotheses about when, where, and by whom PIE was spoken. The [Kurgan hypothesis](/source/Kurgan_hypothesis), first put forward in 1956 by [Marija Gimbutas](/source/Marija_Gimbutas), has become the most popular. It proposes that this proto-language was spoken by the [Yamnaya culture](/source/Yamnaya_culture) in the general area of the [Pontic steppe](/source/Pontic_steppe) north of the Black Sea c. 3400 BCE.[4]: 46[a]

Other theories include the [Anatolian hypothesis](/source/Anatolian_hypothesis),[27] which posits that PIE spread out from Anatolia with agriculture beginning c. 7500–6000 BCE,[28] the [Armenian hypothesis](/source/Armenian_hypothesis), the [Paleolithic continuity paradigm](/source/Paleolithic_continuity_paradigm), and the [indigenous Aryans](/source/Indigenous_Aryans) theory. The last two of these theories are not regarded as credible within academia.[29][30] Out of all the theories for a PIE homeland, the Kurgan and Anatolian hypotheses are the ones most widely accepted, and also the ones most debated against each other.[18] Following the publication of several studies on ancient DNA in 2015, [Colin Renfrew](/source/Colin_Renfrew), the original author and proponent of the Anatolian hypothesis, has accepted the reality of migrations of populations speaking one or several Indo-European languages from the Pontic steppe towards Northwestern Europe.[31][32]

Classification of Indo-European languages.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] Red: Extinct languages. White: categories or unattested proto-languages. Left half: [centum](/source/Centum) languages; right half: [satem](/source/Satem) languages

## Descendants

Main article: [Indo-European languages](/source/Indo-European_languages)

The antiquity of the earliest attestation (in units of 500 years) of each Indo-European group is: 2000–1500 BCE for Anatolian; 1500–1000 BCE for Indo-Aryan and Greek; 1000–500 BCE for Iranic, Celtic, Italic, Phrygian, Illyric, Messapic, South Picene, and Venetic; 500–1 BCE for Thracian and Ancient Macedonian; 1–500 CE for Germanic, Armenian, Lusitanian, and Tocharian; 500–1000 CE for Slavic; 1500–2000 CE for Albanian and Baltic.[18]: 14

The table lists the main Indo-European language families, comprising the languages descended from Proto-Indo-European.

Clade Proto-language Description Historical languages Modern descendants Anatolian Proto-Anatolian All now extinct, the best attested being the Hittite language. Hittite, Luwian, Palaic, Lycian, Lydian, Carian, Pisidian, Sidetic, Milyan There are no living descendants of Proto-Anatolian. Tocharian Proto-Tocharian An extinct branch known from manuscripts dating from the 6th to the 8th century AD and found in northwest China. Tocharian A, Tocharian B There are no living descendants of Proto-Tocharian. Italic Proto-Italic This included many languages, but only descendants of Latin (the Romance languages) survive. Latin, Faliscan, Umbrian, Oscan, African Romance, Dalmatian, Volscian, Marsi, Pre-Samnite, Paeligni, Sabine Portuguese, Galician, Spanish, Ladino, Catalan, Occitan, French, Italian, Friulian, Romansh, Romanian, Aromanian, Sardinian, Corsican, Venetian, Latin (as a liturgical language of the Catholic Church and the official language of the Vatican City), Picard, Mirandese, Aragonese, Walloon, Piedmontese, Lombard, Neapolitan, Sicilian, Emilian-Romagnol, Ligurian, Ladin Celtic Proto-Celtic Once spoken across Europe and Anatolia (Asia Minor), but now mostly confined to Europe's northwestern edge. Gaulish, Lepontic, Noric, Pictish, Cumbric, Old Irish, Middle Welsh, Gallaecian, Galatian, Celtiberian Irish, Scottish Gaelic, Welsh, Breton, Cornish, Manx Germanic Proto-Germanic Branched into three subfamilies: West Germanic, East Germanic (now extinct), and North Germanic. Old English, Old Norse, Gothic, Old High German, Old Saxon, Vandalic, Burgundian, Crimean Gothic, Norn, Greenlandic Norse English, German, Afrikaans, Dutch, Yiddish, Norwegian, Danish, Swedish, Frisian, Icelandic, Faroese, Luxembourgish, Scots, Limburgish, Wymysorys, Elfdalian Balto-Slavic Proto-Balto-Slavic Branched into the Baltic languages and the Slavic languages. Old Prussian, Old Church Slavonic, Sudovian, Semigallian, Selonian, Skalvian, Galindian, Polabian, Knaanic Baltic: Latvian, Latgalian and Lithuanian; Slavic: Russian, Ukrainian, Belarusian, Polish, Czech, Slovak, Sorbian, Serbo-Croatian, Bulgarian, Slovenian, Macedonian, Kashubian, Rusyn Indo-Iranian Proto-Indo-Iranian Branched into the Indo-Aryan, Iranian and Nuristani languages. Vedic Sanskrit, Pali, Prakrit languages; Old Persian, Parthian, Old Azeri, Median, Elu, Sogdian, Saka, Avestan, Bactrian Indo-Aryan: Hindustani (Hindi and Urdu), Marathi, Sylheti, Bengali, Assamese, Odia, Konkani, Gujarati, Nepali, Dogri, Romani, Sindhi, Maithili, Sinhala, Dhivehi, Punjabi, Kashmiri, Sanskrit (revived); Iranian: Persian, Pashto, Balochi, Kurdish, Zaza, Ossetian, Luri, Talyshi, Tati, Gilaki, Mazandarani, Semnani, Yaghnobi; Nuristani: Katë, Prasun, Ashkun, Nuristani Kalasha, Tregami, Zemiaki Armenian Proto-Armenian Armenian is the only surviving representative of the Armenian branch of the Indo-European language family. Classical Armenian Armenian (Eastern and Western) Hellenic Proto-Greek Modern Greek and Tsakonian are the only surviving varieties of Greek. Ancient Greek, Ancient Macedonian Greek, Tsakonian Albanian Proto-Albanian Albanian is the only surviving representative of the Albanoid branch of the Indo-European language family.[33][34] Illyrian (disputed); Daco-Thracian (disputed) Albanian (Gheg and Tosk)

Commonly proposed subgroups of Indo-European languages include [Italo-Celtic](/source/Italo-Celtic), [Graeco-Aryan](/source/Graeco-Aryan), [Graeco-Armenian](/source/Graeco-Armenian), [Graeco-Phrygian](/source/Graeco-Phrygian), [Daco-Thracian](/source/Daco-Thracian), and [Thraco-Illyrian](/source/Thraco-Illyrian).

There are numerous lexical similarities between the Proto-Indo-European and [Proto-Kartvelian](/source/Proto-Kartvelian_language) languages due to early [language contact](/source/Language_contact),[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] as well as some morphological similarities—notably the [Indo-European ablaut](/source/Indo-European_ablaut), which is remarkably similar to the root ablaut system reconstructible for Proto-Kartvelian.[35][36]

### Marginally attested languages

The [Lusitanian language](/source/Lusitanian_language) was a marginally attested language spoken in areas near the border between present-day [Portugal](/source/Portugal) and [Spain](/source/Spain). The [Venetic](/source/Venetic_language) and [Liburnian](/source/Liburnian_language) languages known from the North Adriatic region are sometimes classified as Italic.

Albanian and Greek are the only surviving Indo-European descendants of a [Paleo-Balkan](/source/Paleo-Balkan_languages) language area, named for their occurrence in or in the vicinity of the [Balkan peninsula](/source/Balkan_peninsula). Most of the other languages of this area—including [Illyrian](/source/Illyrian_languages), [Thracian](/source/Thracian_language), and [Dacian](/source/Dacian_language)—do not appear to be members of any other subfamilies of PIE, but are so poorly attested that proper classification of them is not possible. Forming an exception, [Phrygian](/source/Phrygian_language) is sufficiently well-attested to allow proposals of a particularly close affiliation with Greek, and a [Graeco-Phrygian](/source/Graeco-Phrygian) branch of Indo-European is becoming increasingly accepted.[37][38][39]

## Phonology

Main article: [Proto-Indo-European phonology](/source/Proto-Indo-European_phonology)

Proto-Indo-European [phonology](/source/Phonology) has been reconstructed in some detail. Notable features of the most widely accepted (but not uncontroversial) reconstruction include:

- three series of [stop consonants](/source/Stop_consonant) reconstructed as [voiceless](/source/Voiceless_consonant), [voiced](/source/Voiced_consonant), and [breathy voiced](/source/Breathy_voice);

- [sonorant](/source/Sonorant) consonants that could be used [syllabically](/source/Syllabic_consonant);

- three so-called [laryngeal](/source/Laryngeal_theory) consonants, whose exact pronunciation is not well-established but which are believed to have existed in part based on their detectable effects on adjacent sounds;

- the [fricative](/source/Fricative) /s/

- a [vowel](/source/Vowel) system in which /e/ and /o/ were the most frequently occurring vowels. The existence of /a/ as a separate phoneme is debated.

### Notation

#### Vowels

The vowels in commonly used notation are:[40]: 13

Type front back Mid *e /e/, *ē /eː/ *o /o/, *ō /oː/ Low (*a /a/, *ā /aː/)

#### Consonants

The corresponding consonants in commonly used notation are:[4]: §3.2[41]: §11

Labial Dental or Alveolar Velar Laryngeal palatalised plain labialised velar or uvular glottal Nasals *m /m/ *n /n/ *n [ŋ] Stops voiceless *p /p/ *t /t/ *ḱ /kʲ/ *k /k/ *kʷ /kʷ/ voiced *b /b/ *d /d/ *ǵ /gʲ/ *g /ɡ/ *gʷ /ɡʷ/ aspirated *bʰ /bʱ/ *dʰ /dʱ/ *ǵʰ /gʲʱ/ *gʰ /ɡʱ/ *gʷʰ /ɡʷʱ/ Fricatives *s /s/, [z] *h₃ /ɣʷ/~/qʷː/ *h₂ /x/~/qː/ *h₁ /h/~/ʔ/ Laryngeal Pronunciation (J. E. Rasmussen, Kloekhorst) [ɵ] [ɐ] [ə] Syllabic allophone Liquids Trill *r /r/ Lateral *l /l/ Semivowels *y /j/ *w /w/ *i [i] *u [u] Syllabic allophone[40]: 14

All [sonorants](/source/Sonorant) (i.e. nasals, liquids and semivowels) can appear in [syllabic](/source/Syllabic_consonant) position (commonly indicated by an [underring](/source/Ring_(diacritic)) for nasals and liquids). The syllabic allophones of **y* and **w* are realized as the surface vowels **i* and **u* respectively.[40]: 14

[[z](/source/Voiced_alveolar_fricative)] is an allophone of **s* when next to a voiced consonant in certain positions.

[[ŋ](/source/Voiced_velar_nasal)] is an allophone of **n* before velar consonants.

### Accent

The [Proto-Indo-European accent](/source/Proto-Indo-European_accent) is reconstructed today as having had variable lexical stress, which could appear on any syllable and whose position often varied among different members of a paradigm (e.g. between singular and plural of a verbal paradigm). Stressed syllables received a higher pitch and it is often said that PIE had a [pitch accent](/source/Pitch-accent_language). The location of the stress is associated with ablaut variations, especially between full-grade vowels (/e/ and /o/) and zero-grade (i.e. lack of a vowel), but not entirely predictable from it.

The accent is best preserved in [Vedic Sanskrit](/source/Vedic_Sanskrit) and (in the case of nouns) [Ancient Greek](/source/Ancient_Greek), and indirectly attested in a number of phenomena in other IE languages, such as [Verner's Law](/source/Verner's_Law) in the Germanic branch. Sources for Indo-European accentuation are also the [Balto-Slavic](/source/Balto-Slavic_languages) accentual system and *plene* spelling in [Hittite](/source/Hittite_language) cuneiform. To account for mismatches between the accent of Vedic Sanskrit and Ancient Greek, as well as a few other phenomena, a few historical linguists prefer to reconstruct PIE as a [tone language](/source/Tone_(linguistics)) where each [morpheme](/source/Morpheme) had an inherent tone; the sequence of tones in a word then evolved, according to that hypothesis, into the placement of lexical stress in different ways in different IE branches.[42]

## Morphology

Proto-Indo-European, like its earliest attested descendants, was a highly inflected, [fusional language](/source/Fusional_language). Suffixation and ablaut were the main methods of marking inflection, both for nominals and verbs. The subject of a sentence was in the nominative case and agreed in number and person with the verb, which was additionally marked for voice, tense, aspect, and mood.[43]

### Root

Main article: [Proto-Indo-European root](/source/Proto-Indo-European_root)

Proto-Indo-European nominals and verbs were primarily composed of roots – [affix](/source/Affix)-lacking [morphemes](/source/Morpheme) that carried the core [lexical](/source/Lexical_(semiotics)) meaning of a word. They were used to derive related words (cf. the English root "-*friend*-", from which are derived related words such as *friendship,* *friendly*, *befriend*, and newly coined words such as *unfriend*). As a rule, roots were monosyllabic, and had the structure (s)(C)CVC(C), where the symbols C stand for consonants, V stands for a variable vowel, and optional components are in parentheses. All roots ended in a consonant and, although less certain, they appear to have started with a consonant as well.[43]

A root plus a [suffix](/source/Suffix) formed a [word stem](/source/Word_stem), and a word stem plus an [inflectional ending](/source/Suffix#Inflectional_suffixes) formed a word. Proto-Indo-European was a [fusional language](/source/Fusional_language), in which [inflectional](/source/Inflection) morphemes signaled the grammatical relationships between words. This dependence on inflectional morphemes means that roots in PIE, unlike those in English, were rarely used without affixes.[4]: §4.2, §4.20

### Ablaut

Main article: [Indo-European ablaut](/source/Indo-European_ablaut)

Many morphemes in Proto-Indo-European had short *e* as their inherent vowel; the [Indo-European ablaut](/source/Indo-European_ablaut) is the change of this short *e* to short *o*, long *e* (*ē*), long *o* (*ō*), or no vowel. The forms are referred to as the "ablaut grades" of the morpheme—the *e*-grade, *o*-grade, zero-grade (no vowel), etc. This variation in vowels occurred both within [inflectional morphology](/source/Inflectional_morphology) (e.g., different grammatical forms of a noun or verb may have different vowels) and [derivational morphology](/source/Derivational_morphology) (e.g., a verb and an associated abstract [verbal noun](/source/Verbal_noun) may have different vowels).[4]: 73–74

Categories that PIE distinguished through ablaut were often also identifiable by contrasting endings, but the loss of these endings in some later Indo-European languages has led them to use ablaut alone to identify grammatical categories, as in the Modern English words *sing*, *sang*, *sung*.

### Noun

[Proto-Indo-European nouns](/source/Proto-Indo-European_nominals) were probably declined for eight or nine cases:[4]: 102

- [nominative](/source/Nominative_case): marks the [subject](/source/Subject_(grammar)) of a verb. Words that follow a linking verb ([copulative verb](/source/Copulative_verb)) and restate the subject of that verb also use the nominative case. The nominative is the dictionary form of the noun.

- [accusative](/source/Accusative_case): used for the [direct object](/source/Direct_object) of a [transitive verb](/source/Transitive_verb).

- [genitive](/source/Genitive_case): marks a [noun](/source/Noun) as modifying another noun.

- [dative](/source/Dative_case): used to indicate the indirect object of a transitive verb, such as *Jacob* in *Maria gave Jacob a drink*.

- [instrumental](/source/Instrumental_case): marks the *instrument* or means by, or with, which the subject achieves or accomplishes an action. It may be either a physical object or an abstract concept.

- [ablative](/source/Ablative_case): used to express motion away from something.

- [locative](/source/Locative_case): expresses location, corresponding vaguely to the English prepositions *in*, *on*, *at*, and *by*.

- [vocative](/source/Vocative_case): used for a word that identifies an addressee. A vocative is a [noun of address](/source/Noun_of_address) where the identity of the party spoken to is set forth expressly within a sentence. For example, in the sentence, "I don't know, John", *John* is a noun of address, indicating the party being addressed.

- [allative](/source/Allative_case): used as a type of [locative case](/source/Locative_case) that expresses movement towards something. It was preserved in Anatolian (particularly Old Hittite), and fossilized traces of it have been found in Greek. It is also present in Tocharian.[44] Its PIE shape is uncertain, with candidates including **-h₂(e)*, **-(e)h₂*, or **-a*.[4]: 102, 105

Late Proto-Indo-European had three [grammatical genders](/source/Grammatical_gender):

- masculine

- feminine

- neuter

This system is probably derived from an older two-gender system, attested in Anatolian languages: [common](/source/Common_gender) (or [animate](/source/Animate_gender)) and neuter (or inanimate) gender. The feminine gender only arose in the later period of the language.[45] Neuter nouns collapsed the nominative, vocative and accusative into a single form, the plural of which used a special [collective](/source/Collective_noun) suffix *[*-h₂](https://en.wiktionary.org/wiki/Reconstruction:Proto-Indo-European/-h%E2%82%82#Proto-Indo-European)* (manifested in most descendants as *-a*). This same collective suffix in extended forms *[*-eh₂](https://en.wiktionary.org/wiki/Reconstruction:Proto-Indo-European/-%C3%A9h%E2%82%82#Proto-Indo-European)* and *[*-ih₂](https://en.wiktionary.org/wiki/Reconstruction:Proto-Indo-European/-ih%E2%82%82#Proto-Indo-European)* (respectively on thematic and athematic nouns, becoming *-ā* and *-ī* in the early daughter languages) became used to form feminine nouns from masculines.

All nominals distinguished three [numbers](/source/Grammatical_number):

- singular

- dual

- plural

These numbers were also distinguished in verbs (see [below](#Verb)), requiring [agreement](/source/Agreement_(linguistics)) with their subject nominal.

### Pronoun

[Proto-Indo-European pronouns](/source/Proto-Indo-European_pronouns) are difficult to reconstruct, owing to their variety in later languages. PIE had personal [pronouns](/source/Pronoun) in the first and second [grammatical person](/source/Grammatical_person), but not the third person, where [demonstrative pronouns](/source/Demonstrative_pronoun) were used instead. The personal pronouns had their own unique forms and endings, and some had [two distinct stems](/source/Suppletion); this is most obvious in the first person singular where the two stems are still preserved in English *I* and *me*. There were also two varieties for the accusative, genitive and dative cases, a stressed and an [enclitic](/source/Enclitic) form.[41]: 147, 212–217, 233, 243

Personal pronouns[41] Case First person Second person Singular Plural Singular Plural Nominative *h₁eǵ(oH/Hom) *wei *tuH *yuH Accusative *h₁mé, *h₁me *n̥smé, *nōs *twé *usmé, *wōs Genitive *h₁méne, *h₁moi *n̥s(er)o-, *nos *tewe, *toi *yus(er)o-, *wos Dative *h₁méǵʰio, *h₁moi *n̥smei, *n̥s *tébʰio, *toi *usmei Instrumental *h₁moí *n̥smoí *toí *usmoí Ablative *h₁med *n̥smed *tued *usmed Locative *h₁moí *n̥smi *toí *usmi

### Verb

[Proto-Indo-European verbs](/source/Proto-Indo-European_verbs), like the nouns, exhibited an ablaut system.

The most basic categorisation for the reconstructed Indo-European verb is [grammatical aspect](/source/Grammatical_aspect). Verbs are classed as:

- [stative](/source/Stative_verb): verbs that depict a state of being

- [imperfective](/source/Imperfective_aspect): verbs depicting ongoing, habitual or repeated action

- [perfective](/source/Perfective_aspect): verbs depicting a completed action or actions viewed as an entire process.

Verbs have at least four [grammatical moods](/source/Grammatical_mood):

- [indicative](/source/Indicative_mood): indicates that something is a statement of fact; in other words, to express what the speaker considers to be a known state of affairs, as in [declarative sentences](/source/Declarative_sentence).

- [imperative](/source/Imperative_mood): forms commands or requests, including the giving of prohibition or permission, or any other kind of advice or exhortation.

- [subjunctive](/source/Subjunctive_mood): used to express various states of unreality such as wish, emotion, possibility, judgment, opinion, obligation, or action that has not yet occurred

- [optative](/source/Optative_mood): indicates a wish or hope. It is similar to the [cohortative mood](/source/Cohortative_mood) and is closely related to the [subjunctive mood](/source/Subjunctive_mood).

Verbs had two [grammatical voices](/source/Grammatical_voice):

- [active](/source/Active_voice): used in a clause whose subject expresses the main verb's [agent](/source/Agent_(grammar)).

- [mediopassive](/source/Mediopassive_voice): for the [middle voice](/source/Middle_voice) and the [passive voice](/source/Passive_voice).

Verbs had three [grammatical persons](/source/Grammatical_person): first, second and third.

Verbs had three [grammatical numbers](/source/Grammatical_number):

- singular

- [dual](/source/Dual_grammatical_number): referring to precisely two of the entities (objects or persons) identified by the noun or pronoun.

- [plural](/source/Plural): a number other than singular or dual.

Verbs were probably marked by a highly developed system of [participles](/source/Participle), one for each combination of tense and voice, and an assorted array of [verbal nouns](/source/Verbal_noun) and adjectival formations.

The following table shows a possible reconstruction of the PIE verb endings from Sihler, which largely represents the current consensus among Indo-Europeanists.

Person Sihler (1995)[46] Athematic Thematic Singular 1st *-mi *-oh₂ 2nd *-si *-esi 3rd *-ti *-eti Dual 1st *-wos *-owos 2nd *-th₁es *-eth₁es 3rd *-tes *-etes Plural 1st *-mos *-omos 2nd *-te *-ete 3rd *-nti *-onti

### Numbers

[Proto-Indo-European numerals](/source/Proto-Indo-European_numerals) are generally reconstructed as follows:

Number Sihler[46] one *(H)óynos/*(H)óywos/*(H)óyk(ʷ)os; *sḗm (full grade), *sm̥- (zero grade) two *d(u)wóh₁ (full grade), *dwi- (zero grade) three *tréyes (full grade), *tri- (zero grade) four *kʷetwóres (o-grade), *kʷ(e)twr̥- (zero grade) (see also the *kʷetwóres rule) five *pénkʷe six *s(w)éḱs; originally perhaps *wéḱs, with *s- under the influence of *septḿ̥ seven *septḿ̥ eight *oḱtṓ(w) or *h₃eḱtṓ(w) nine *h₁néwn̥ ten *déḱm̥(t)

Rather than specifically 100, **ḱm̥tóm* may originally have meant "a large number".[47]

### Particle

[Proto-Indo-European particles](/source/Proto-Indo-European_particles) were probably used both as [adverbs](/source/Adverb) and as [postpositions](/source/Preposition_and_postposition). These postpositions became prepositions in most daughter languages.

Reconstructed particles include for example, **upo* "under, below"; the [negators](/source/Affirmative_and_negative) **ne*, **mē*; the [conjunctions](/source/Conjunction_(grammar)) **kʷe* "and", **wē* "or" and others; and an [interjection](/source/Interjection), **wai!*, expressing woe or agony.

### Derivational morphology

Proto-Indo-European employed various means of deriving words from other words, or directly from verb roots.

#### Internal derivation

Internal derivation was a process that derived new words through changes in accent and ablaut alone. It was not as productive as external (affixing) derivation, but is firmly established by the evidence of various later languages.

#### Possessive adjectives

Possessive or associated adjectives were probably created from nouns through internal derivation. Such words could be used directly as adjectives, or they could be turned back into a noun without any change in morphology, indicating someone or something characterised by the adjective. They were probably also used as the second elements in compounds. If the first element was a noun, this created an adjective that resembled a present participle in meaning, e.g. "having much rice" or "cutting trees". When turned back into nouns, such compounds were [Bahuvrihis](/source/Bahuvrihi) or semantically resembled [agent nouns](/source/Agent_noun).

In thematic stems, creating a possessive adjective seems to have involved shifting the accent one syllable to the right, for example:[48]: 21

- **tómh₁-o-s* "slice" ([Ancient Greek](/source/Ancient_Greek) τόμος *tómos*) > **tomh₁-ó-s* "cutting" (i.e. "making slices"; Greek τομός *tomós*) > **dr-u-tomh₁-ó-s* "cutting trees" (Greek δρυτόμος *drutómos* "woodcutter" with irregular accent).

- **wólh₁-o-s* "wish" ([Vedic Sanskrit](/source/Vedic_Sanskrit) वर॑ *vára*) > **wolh₁-ó-s* "having wishes" (Sanskrit व॒र *vará* "suitor").

In athematic stems, there was a change in the accent/ablaut class. The reconstructed four classes followed an ordering in which a derivation would shift the class one to the right:[48]: 21

- acrostatic → proterokinetic → hysterokinetic → amphikinetic

The reason for this particular ordering of the classes in derivation is not known. Some examples:

- Acrostatic **krót-u-s* ~ **krét-u-s* "strength" (Sanskrit क्रतु॑ *krátu* > proterokinetic **krét-u-s* ~ **kr̥t-éw-s* "having strength, strong" (Greek κρατύς *kratús*).

- Hysterokinetic **ph₂-tḗr* ~ **ph₂-tr-és* "father" (Greek πατήρ *patḗr*) > amphikinetic **h₁su-péh₂-tōr* ~ **h₁su-ph₂-tr-és* "having a good father" (Greek εὐπάτωρ *eupátōr*).

#### Vṛddhi

A [vṛddhi](/source/V%E1%B9%9Bddhi) derivation, named after the Sanskrit grammatical term, signifying "of, belonging to, descended from". It was characterised by "upgrading" the root grade, from zero to full (*e*) or from full to lengthened (*ē*). When upgrading from zero to full grade, the vowel could sometimes be inserted in an unexpected location, creating a different stem from the original full grade.

Examples:[4]: 116f

- full grade **sw**é**ḱuro-s* "father-in-law" ([Vedic Sanskrit](/source/Vedic_Sanskrit) श्वशु॑र *śv**á**śura-*) > lengthened grade **sw**ē**ḱuró-s* "relating to one's father-in-law" (Sanskrit श्वाशुर *śv**ā**śura*, [Old High German](/source/Old_High_German) *swāgur* "brother-in-law").

- full grade **dyḗw-s* > zero grade **diw-és* "sky" (Sanskrit द्यौस् *dy**á**us*) > new full grade **d**e**yw-o-s* "god, [sky god](/source/Dyeus)" (Sanskrit दे॒वस् *d**e**vás*, [Ancient Greek](/source/Ancient_Greek) Ζεύς *Z**e**ús*, [Latin](/source/Latin) *d**e**us*, etc.). Note the difference in vowel placement, **dyew-* in the full-grade stem of the original noun, but **deyw-* in the vṛddhi derivative.

#### Nominalization

Adjectives with accent on the thematic vowel could be turned into nouns by moving the accent back onto the root. A zero grade root could remain so, or be "upgraded" to full grade like in a vṛddhi derivative. Some examples:[48]: 22

- PIE **ǵn̥h₁-tó-s* ("born"; [Vedic Sanskrit](/source/Vedic_Sanskrit) जा॒त *jātá*) > **ǵénh₁-to-* ("child", literally "thing that is born"; Sanskrit जात *jāta*; German *Kind*).

- [Ancient Greek](/source/Ancient_Greek) λευκός *leukós* ("white") > λεῦκος *leûkos* (*a kind of fish*, literally "white one").

- Sanskrit कृ॒ष्ण *kṛṣṇá* ("dark") > कृष्ण॑स् *kṛ́ṣṇas* ("antelope", literally "dark one").

This kind of derivation is likely related to the possessive adjectives, and can be seen as essentially the reverse of it.

#### Affixal derivation

This section is empty. You can help by adding to it. (May 2019)

## Syntax

The [syntax](/source/Syntax) of the older Indo-European languages has been studied in earnest since at least the late nineteenth century, by such scholars as [Hermann Hirt](/source/Hermann_Hirt) and [Berthold Delbrück](/source/Berthold_Delbr%C3%BCck). In the second half of the twentieth century, interest in the topic increased and led to reconstructions of Proto-Indo-European syntax.[49]

Since all the early attested IE languages were inflectional, PIE is thought to have relied primarily on morphological markers, rather than [word order](/source/Word_order), to signal [syntactic](/source/Syntax) relationships within sentences.[50] Still, a default ([unmarked](/source/Markedness)) word order is thought to have existed in PIE. In 1892, [Jacob Wackernagel](/source/Jacob_Wackernagel) reconstructed PIE's word order as [subject–verb–object](/source/Subject%E2%80%93verb%E2%80%93object) (SVO), based on evidence in Vedic Sanskrit.[51]

[Winfred P. Lehmann](/source/Winfred_P._Lehmann) (1974), on the other hand, reconstructs PIE as a [subject–object–verb](/source/Subject%E2%80%93object%E2%80%93verb) (SOV) language. He posits that the presence of [person marking](/source/Grammatical_person) in PIE verbs motivated a shift from OV to VO order in later dialects. Many of the descendant languages have VO order: modern Greek, [Romance](/source/Romance_languages) and [Albanian](/source/Albanian_language) prefer SVO, [Insular Celtic](/source/Insular_Celtic) has VSO as the default order, and even the [Anatolian languages](/source/Anatolian_languages) show some signs of this word order shift. [Tocharian](/source/Tocharian_languages) and [Indo-Iranian](/source/Indo-Iranian_languages), meanwhile, retained the conservative OV order. Lehmann attributes the context-dependent order preferences in Baltic, Slavic and Germanic to outside influences.[52] [Donald Ringe](/source/Donald_Ringe) (2006), however, attributes these to internal developments instead.[53]

[Paul Friedrich](/source/Paul_Friedrich_(linguist)) (1975) disagrees with Lehmann's analysis. He reconstructs PIE with the following syntax:

- basic SVO word order

- adjectives before nouns

- head nouns before [genitives](/source/Genitive)

- [prepositions](/source/Prepositions) rather than postpositions

- no dominant order in [comparative constructions](/source/Comparison_(grammar))

- main clauses before [relative clauses](/source/Relative_clauses)

Friedrich notes that even among those Indo-European languages with basic OV word order, none of them are *rigidly* OV. He also notes that these non-rigid OV languages mainly occur in parts of the IE area that overlap with OV languages from other families (such as [Uralic](/source/Uralic) and [Dravidian](/source/Dravidian_languages)), whereas VO is predominant in the central parts of the IE area. For these reasons, among others, he argues for a VO common ancestor.[54]

[Hans Henrich Hock](/source/Hans_Henrich_Hock) (2015) reports that the SVO hypothesis still has some adherents, but the "broad consensus" among PIE scholars is that PIE would have been an SOV language.[51] The SOV default word order with other orders used to express emphasis (e.g., [verb–subject–object](/source/Verb%E2%80%93subject%E2%80%93object) to emphasise the verb) is attested in [Old Indo-Aryan](/source/Old_Indo-Aryan), [Old Iranian](/source/Old_Iranian), [Old Latin](/source/Old_Latin) and [Hittite](/source/Hittite_language), while traces of it can be found in the [enclitic](/source/Enclitic) personal pronouns of the [Tocharian languages](/source/Tocharian_languages).[50]

## See also

- [Indo-European vocabulary](/source/Indo-European_vocabulary)

- [Proto-Indo-European verbs](/source/Proto-Indo-European_verbs)

- [Proto-Indo-European pronouns](/source/Proto-Indo-European_pronouns)

- [List of Indo-European languages](/source/List_of_Indo-European_languages)

- [Indo-European sound laws](/source/Indo-European_sound_laws)

- [List of proto-languages](/source/List_of_proto-languages)

- [Schleicher's fable](/source/Schleicher's_fable)

- *[The king and the god](/source/The_king_and_the_god)*

## Notes

1. **[^](#cite_ref-27)** See: - Bomhard: "This scenario is supported not only by linguistic evidence, but also by a growing body of archeological and genetic evidence. The Indo-Europeans have been identified with several cultural complexes existing in that area between 4,500—3,500 BCE. The literature supporting such a homeland is both extensive and persuasive [...]. Consequently, other scenarios regarding the possible Indo-European homeland, such as Anatolia, have now been mostly abandoned."[19] - Anthony & Ringe: "Archaeological evidence and linguistic evidence converge in support of an origin of Indo-European languages on the Pontic-Caspian steppes around 4,000 years BCE. The evidence is so strong that arguments in support of other hypotheses should be reexamined."[20] - Mallory: "The Kurgan solution is attractive and has been accepted by many archaeologists and linguists, in part or total. It is the solution one encounters in the *Encyclopædia Britannica* and the *Grand Dictionnaire Encyclopédique Larousse*."[21] - Strazny: "The single most popular proposal is the Pontic steppes (see the [Kurgan](/source/Kurgan) hypothesis)..."[22] It proposes that the original speakers of PIE were the [Yamnaya culture](/source/Yamnaya_culture) associated with the kurgans (burial mounds) on the [Pontic–Caspian steppe](/source/Pontic%E2%80%93Caspian_steppe) north of the Black Sea.[23]: 305–7[24] According to the theory, they were [nomadic pastoralists](/source/Eurasian_nomads) who [domesticated the horse](/source/Domestication_of_the_horse), which allowed them to migrate across Europe and Asia in wagons and chariots.[24] By the early 3rd millennium BCE, they had expanded throughout the Pontic–Caspian steppe and into eastern Europe.[25] In 2024, a pair of studies led by Harvard biologist [David Reich](/source/David_Reich_(geneticist)) argued that the original speakers of PIE originated in the Caucusus-Lower Volga region during the [Eneolithic Period](/source/Eneolithic_Period).[26]

## References

1. **[^](#cite_ref-1)** ["Indo-European languages"](https://www.britannica.com/topic/Indo-European-languages). *Encyclopædia Britannica*. The parent language: Proto-Indo-European. Retrieved 19 September 2021.

1. **[^](#cite_ref-2)** Ivić, Pavle; Hamp, Eric P.; Lyons, John (5 March 2024). ["Linguistics"](https://www.britannica.com/science/linguistics/The-comparative-method). *Encyclopædia Britannica*. Retrieved 9 August 2024.

1. **[^](#cite_ref-3)** Powell, Eric A. (September–October 2013). ["Wolf Rites of Winter"](https://archaeology.org/issues/september-october-2013/features/timber-grave-culture-krasnosamarskoe-bronze-age/). *[Archaeology](/source/Archaeology_(magazine))*. [ISSN](/source/ISSN_(identifier)) [0003-8113](https://search.worldcat.org/issn/0003-8113). Retrieved 23 April 2025.

1. ^ [***a***](#cite_ref-Fortson_2010_4-0) [***b***](#cite_ref-Fortson_2010_4-1) [***c***](#cite_ref-Fortson_2010_4-2) [***d***](#cite_ref-Fortson_2010_4-3) [***e***](#cite_ref-Fortson_2010_4-4) [***f***](#cite_ref-Fortson_2010_4-5) [***g***](#cite_ref-Fortson_2010_4-6) [***h***](#cite_ref-Fortson_2010_4-7) Fortson, Benjamin W. (2010). *Indo-European language and culture: an introduction* (2nd ed.). Malden, Massachusetts: Blackwell. [ISBN](/source/ISBN_(identifier)) [978-1-405-18896-8](https://en.wikipedia.org/wiki/Special:BookSources/978-1-405-18896-8).

1. **[^](#cite_ref-5)** ["Linguistics – The comparative method"](https://www.britannica.com/science/linguistics/The-comparative-method#toc35116). *Encyclopedia Britannica*. Science. Retrieved 27 July 2016.

1. **[^](#cite_ref-comp-ling_6-0)** ["Comparative linguistics"](https://www.britannica.com/science/comparative-linguistics). *Encyclopædia Britannica*. Retrieved 27 August 2016.

1. **[^](#cite_ref-7)** ["Sir William Jones, British orientalist and jurist"](https://www.britannica.com/biography/William-Jones-British-orientalist-and-jurist). *Encyclopædia Britannica*. Retrieved 3 September 2016.

1. **[^](#cite_ref-auroux_8-0)** Auroux, Sylvain (2000). [*History of the Language Sciences*](https://books.google.com/books?id=yasNy365EywC&q=3110167352&pg=PA1156). [Walter de Gruyter](/source/Walter_de_Gruyter). p. 1156. [ISBN](/source/ISBN_(identifier)) [3-11-016735-2](https://en.wikipedia.org/wiki/Special:BookSources/3-11-016735-2).

1. **[^](#cite_ref-Blench_9-0)** [Blench, Roger](/source/Roger_Blench) (2004). "Archaeology and language: Methods and issues". In Bintliff, J. (ed.). [*A Companion to Archaeology*](http://www.rogerblench.info/Archaeology/World/CH4-BLENCH.pdf) (PDF). Oxford, UK: Basil Blackwell. pp. 52–74.

1. **[^](#cite_ref-10)** Wheeler, Kip. ["The Sanskrit Connection: Keeping Up With the Joneses"](http://web.cn.edu/kwheeler/IE_Main4_Sanskrit.html). [Carson–Newman University](/source/Carson%E2%80%93Newman_University). Retrieved 16 April 2013.

1. **[^](#cite_ref-11)** [Momma, Haruko](/source/Haruko_Momma) (2013). [*From Philology to English Studies: Language and Culture in the Nineteenth Century*](https://books.google.com/books?id=WGYzp7olz6QC). [Cambridge University Press](/source/Cambridge_University_Press). pp. 65–66. [ISBN](/source/ISBN_(identifier)) [978-0-521-51886-4](https://en.wikipedia.org/wiki/Special:BookSources/978-0-521-51886-4).

1. **[^](#cite_ref-12)** ["Franz Bopp, German philologist"](https://www.britannica.com/biography/Franz-Bopp). *Encyclopædia Britannica*. Retrieved 26 August 2016.

1. **[^](#cite_ref-13)** ["Grimm's law, linguistics"](https://www.britannica.com/topic/Grimms-law). *Encyclopædia Britannica*. Retrieved 26 August 2016.

1. **[^](#cite_ref-14)** ["Neogrammarian, German scholar"](https://www.britannica.com/science/Neogrammarian). *Encyclopædia Britannica*. Retrieved 26 August 2016.

1. **[^](#cite_ref-15)** ["August Schleicher, German linguist"](https://www.britannica.com/biography/August-Schleicher). *Encyclopædia Britannica*. Retrieved 26 August 2016.

1. **[^](#cite_ref-16)** Saussure, Ferdinand de (1879). [*Mémoire sur le système primitif des voyelles dans les langues indo-européennes*](http://archive.org/details/memoiresurlesyst00saus). Leipsick: B. G. Teubner – via archive.org. University of California Libraries.

1. **[^](#cite_ref-17)** Kuryłowicz, Jerzy (1927). Taszycki, Witold; Doroszewki, Witold (eds.). "*ə* indo-européen et *ḫ* hittite". *Symbolae Grammaticae in honorem Ioannis Rozwadowski*. **1**. Krakow: Uniwersytet Jagielloński: 95–104.

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1. ^ [***a***](#cite_ref-Science_24-0) [***b***](#cite_ref-Science_24-1) Balter, Michael (13 February 2015). ["Mysterious Indo-European homeland may have been in the steppes of Ukraine and Russia"](https://www.science.org/content/article/mysterious-indo-european-homeland-may-have-been-steppes-ukraine-and-russia). *Science*. [doi](/source/Doi_(identifier)):[10.1126/science.aaa7858](https://doi.org/10.1126%2Fscience.aaa7858). Retrieved 17 February 2015.

1. **[^](#cite_ref-25)** Gimbutas, Marija (1985). "Primary and Secondary Homeland of the Indo-Europeans: comments on Gamkrelidze-Ivanov articles". *Journal of Indo-European Studies*. **13** (1–2): 185–202.

1. **[^](#cite_ref-26)** ["Harvard Researchers Discover Origin of Indo-European Language Family"](https://www.thecrimson.com/article/2025/2/12/indo-european-language-research/). *The Harvard Crimson*. Retrieved 16 June 2025.

1. **[^](#cite_ref-bouckaert_28-0)** Bouckaert, Remco; Lemey, P.; Dunn, M.; Greenhill, S. J.; Alekseyenko, A. V.; Drummond, A. J.; Gray, R. D.; Suchard, M. A.; et al. (24 August 2012), ["Mapping the Origins and Expansion of the Indo-European Language Family"](http://web.archive.org/web/20170817200422/http://pubman.mpdl.mpg.de/pubman/item/escidoc:1539154/component/escidoc:1539165/Bouckaert_2012.pdf) (PDF), *Science*, **337** (6097): 957–960, [Bibcode](/source/Bibcode_(identifier)):[2012Sci...337..957B](https://ui.adsabs.harvard.edu/abs/2012Sci...337..957B), [doi](/source/Doi_(identifier)):[10.1126/science.1219669](https://doi.org/10.1126%2Fscience.1219669), [hdl](/source/Hdl_(identifier)):[11858/00-001M-0000-000F-EADF-A](https://hdl.handle.net/11858%2F00-001M-0000-000F-EADF-A), [PMC](/source/PMC_(identifier)) [4112997](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4112997), [PMID](/source/PMID_(identifier)) [22923579](https://pubmed.ncbi.nlm.nih.gov/22923579), archived from [the original](http://pubman.mpdl.mpg.de/pubman/item/escidoc:1539154/component/escidoc:1539165/Bouckaert_2012.pdf) (PDF) on 17 August 2017

1. **[^](#cite_ref-29)** Chang, Will; Cathcart, Chundra; Hall, David; Garrett, Andrew (2015). ["Ancestry-constrained phylogenetic analysis supports the Indo-European steppe hypothesis"](https://muse.jhu.edu/content/crossref/journals/language/v091/91.1.chang.html). *Language*. **91** (1): 194–244. [doi](/source/Doi_(identifier)):[10.1353/lan.2015.0005](https://doi.org/10.1353%2Flan.2015.0005). [ISSN](/source/ISSN_(identifier)) [1535-0665](https://search.worldcat.org/issn/1535-0665). [S2CID](/source/S2CID_(identifier)) [143978664](https://api.semanticscholar.org/CorpusID:143978664).

1. **[^](#cite_ref-30)** [Thapar, Romila](/source/Romila_Thapar) (2006). [*India: Historical Beginnings and the Concept of the Aryan*](https://books.google.com/books?id=sDBuAAAAMAAJ&q=%22there+is+no+scholar+at+this+time+seriously%22). National Book Trust. p. 127. [ISBN](/source/ISBN_(identifier)) [9788123747798](https://en.wikipedia.org/wiki/Special:BookSources/9788123747798) – via Google Books.

1. **[^](#cite_ref-31)** [Doniger, Wendy](/source/Wendy_Doniger) (2017). ["Another Great Story"](https://web.archive.org/web/20230514094423/https://inference-review.com/article/another-great-story). *inference-review.com*. Archived from [the original](https://inference-review.com/article/another-great-story) (Review) on 14 May 2023. Retrieved 30 December 2025. The opposing argument, that speakers of Indo-European languages were indigenous to the Indian subcontinent, is not supported by any reliable scholarship Review of Parpola, Asko. "The Roots of Hinduism". *Inference, International Review of Science*. **3** (2).

1. **[^](#cite_ref-32)** Renfrew, Colin (8 November 2017). [*Marija Redivia : DNA and Indo-European origins*](https://www.youtube.com/watch?v=pmv3J55bdZc). Chicago: Marija Gimbutas memorial lecture – via YouTube.

1. **[^](#cite_ref-:4_33-0)** Pellard, Thomas; [Sagart, Laurent](/source/Laurent_Sagart); Jacques, Guillaume (2018). "L'indo-européen n'est pas un mythe". *Bulletin de la Société de Linguistique de Paris* (in French). **113** (1): 79–102. [doi](/source/Doi_(identifier)):[10.2143/BSL.113.1.3285465](https://doi.org/10.2143%2FBSL.113.1.3285465). [S2CID](/source/S2CID_(identifier)) [171874630](https://api.semanticscholar.org/CorpusID:171874630).

1. **[^](#cite_ref-34)** Trumper, John (2018). "Some Celto-Albanian isoglosses and their implications". In Grimaldi, Mirko; Lai, Rosangela; Franco, Ludovico; Baldi, Benedetta (eds.). [*Structuring Variation in Romance Linguistics and Beyond: In Honour of Leonardo M. Savoia*](https://books.google.com/books?id=kAR-DwAAQBAJ). John Benjamins Publishing Company. [ISBN](/source/ISBN_(identifier)) [9789027263179](https://en.wikipedia.org/wiki/Special:BookSources/9789027263179). pp. 383–386.

1. **[^](#cite_ref-35)** ["Perfect Phylogenetic Networks: A New Methodology for Reconstructing the Evolutionary History of Natural Languages, pg. 396"](http://www.cs.rice.edu/~nakhleh/Papers/81.2nakhleh.pdf) (PDF). [Archived](https://web.archive.org/web/20101105223804/http://www.cs.rice.edu/~nakhleh/Papers/81.2nakhleh.pdf) (PDF) from the original on 5 November 2010. Retrieved 22 September 2010.

1. **[^](#cite_ref-36)** Gamkrelidze, T. V.; Ivanov, V. V. (1995). *Indo-European and the Indo-Europeans: A Reconstruction and Historical Analysis of a Proto-Language and a Proto-Culture*. Berlin; New York: Mouton de Gruyter.

1. **[^](#cite_ref-37)** Gamkrelidze, Thomas V. (2008). ["Kartvelian and Indo-European: a typological comparison of reconstructed linguistic systems"](https://archive.org/details/GamkrelidzeKartvelianAndIndoEuropeanATypologicalComparisonOfReconstructedLinguisticSystems). *Bulletin of the Georgian National Academy of Sciences*. **2** (2). Georgian National Academy of Sciences: 154–160. Retrieved 30 December 2025 – via archive.org.

1. **[^](#cite_ref-38)** Brixhe, Claude (2008). ["Phrygian"](https://books.google.com/books?id=J-f_jwCgmeUC&pg=PA72). In Woodard, Roger D. (ed.). *The Ancient Languages of Asia Minor*. Cambridge University Press. p. 72. [ISBN](/source/ISBN_(identifier)) [9781139469333](https://en.wikipedia.org/wiki/Special:BookSources/9781139469333).

1. **[^](#cite_ref-39)** Ligorio, Orsat; Lubotsky, Alexander (2018). ["101. Phrygian"](https://www.academia.edu/36922557). In Jared Klein; Brian Joseph; Matthias Fritz (eds.). *Handbook of Comparative and Historical Indo-European Linguistics*. HSK 41.3. Berlin, Boston: De Gruyter Mouton. pp. 1816–1831. [doi](/source/Doi_(identifier)):[10.1515/9783110542431-022](https://doi.org/10.1515%2F9783110542431-022). [hdl](/source/Hdl_(identifier)):[1887/63481](https://hdl.handle.net/1887%2F63481). [ISBN](/source/ISBN_(identifier)) [9783110542431](https://en.wikipedia.org/wiki/Special:BookSources/9783110542431). [S2CID](/source/S2CID_(identifier)) [242082908](https://api.semanticscholar.org/CorpusID:242082908).

1. **[^](#cite_ref-40)** Obrador-Cursach, Bartomeu (2019). ["On the place of Phrygian among the Indo-European languages"](https://doi.org/10.31826%2Fjlr-2019-173-407). *Journal of Language Relationship*. **17** (3–4): 239. [doi](/source/Doi_(identifier)):[10.31826/jlr-2019-173-407](https://doi.org/10.31826%2Fjlr-2019-173-407). [S2CID](/source/S2CID_(identifier)) [215769896](https://api.semanticscholar.org/CorpusID:215769896).

1. ^ [***a***](#cite_ref-Kapović_2017_41-0) [***b***](#cite_ref-Kapović_2017_41-1) [***c***](#cite_ref-Kapović_2017_41-2) Kapović, Mate (2017). "Proto-Indo-European phonology". In Kapović, Mate (ed.). *The Indo-European Languages* (2nd ed.). London: Routledge. [ISBN](/source/ISBN_(identifier)) [978-0-415-73062-4](https://en.wikipedia.org/wiki/Special:BookSources/978-0-415-73062-4).

1. ^ [***a***](#cite_ref-beekes_42-0) [***b***](#cite_ref-beekes_42-1) [***c***](#cite_ref-beekes_42-2) Beekes, Robert (1995). *Comparative Indo-European linguistics: an introduction*. Amsterdam: J. Benjamins Publishing Company. [ISBN](/source/ISBN_(identifier)) [978-1556195044](https://en.wikipedia.org/wiki/Special:BookSources/978-1556195044).

1. **[^](#cite_ref-43)** Kortlandt, Frederik (1986). "Proto-Indo-European Tones". *Journal of Indo-European Studies*: 153–160. [S2CID](/source/S2CID_(identifier)) [55314276](https://api.semanticscholar.org/CorpusID:55314276).

1. ^ [***a***](#cite_ref-ELL_-_PIE_Morphology_44-0) [***b***](#cite_ref-ELL_-_PIE_Morphology_44-1) Brown, Keith, ed. (2006). "Proto-Indo-European Morphology". *Encyclopedia of Language and Linguistics* (2nd ed.). [Elsevier](/source/Elsevier). [ISBN](/source/ISBN_(identifier)) [9780080547848](https://en.wikipedia.org/wiki/Special:BookSources/9780080547848).

1. **[^](#cite_ref-45)** Pinault, Georges-Jean (23 October 2017), ["76. The morphology of Tocharian"](https://www.degruyter.com/document/doi/10.1515/9783110523874-031/html), *Handbook of Comparative and Historical Indo-European Linguistics*, De Gruyter Mouton, pp. 1335–1352, [doi](/source/Doi_(identifier)):[10.1515/9783110523874-031](https://doi.org/10.1515%2F9783110523874-031), [ISBN](/source/ISBN_(identifier)) [978-3-11-052387-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-11-052387-4), retrieved 8 March 2023

1. **[^](#cite_ref-46)** Burrow, T (1955). *The Sanskrit Language*. Motilal Banarsidass Publ. [ISBN](/source/ISBN_(identifier)) [81-208-1767-2](https://en.wikipedia.org/wiki/Special:BookSources/81-208-1767-2). {{[cite book](https://en.wikipedia.org/wiki/Template:Cite_book)}}: ISBN / Date incompatibility ([help](https://en.wikipedia.org/wiki/Help:CS1_errors#invalid_isbn_date))

1. ^ [***a***](#cite_ref-sihler_47-0) [***b***](#cite_ref-sihler_47-1) [Sihler, Andrew L.](/source/Andrew_Sihler) (1995). *New comparative grammar of Greek and Latin*. New York u. a.: Oxford Univ. Press. [ISBN](/source/ISBN_(identifier)) [0-19-508345-8](https://en.wikipedia.org/wiki/Special:BookSources/0-19-508345-8).

1. **[^](#cite_ref-48)** Lehmann, Winfried P (1993), [*Theoretical Bases of Indo-European Linguistics*](https://archive.org/details/theoreticalbases0000lehm/page/252), London: Routledge, pp. [252–55](https://archive.org/details/theoreticalbases0000lehm/page/252), [ISBN](/source/ISBN_(identifier)) [0-415-08201-3](https://en.wikipedia.org/wiki/Special:BookSources/0-415-08201-3)

1. ^ [***a***](#cite_ref-JJasanoff_49-0) [***b***](#cite_ref-JJasanoff_49-1) [***c***](#cite_ref-JJasanoff_49-2) [Jasanoff, Jay](/source/Jay_Jasanoff). *The Prehistory of the Balto-Slavic Accent*.

1. **[^](#cite_ref-50)** Kulikov, Leonid; Lavidas, Nikolaos, eds. (2015). "Preface". *Proto-Indo-European Syntax and its Development*. John Benjamins.

1. ^ [***a***](#cite_ref-eiec_51-0) [***b***](#cite_ref-eiec_51-1) Mallory, J. P.; Adams, Douglas Q., eds. (1997). "Proto-Indo-European". *[Encyclopedia of Indo-European Culture](/source/Encyclopedia_of_Indo-European_Culture)*. Taylor & Francis. p. 463.

1. ^ [***a***](#cite_ref-hock_52-0) [***b***](#cite_ref-hock_52-1) [Hock, Hans Henrich](/source/Hans_Henrich_Hock) (2015). "Proto-Indo-European verb-finality: Reconstruction, typology, validation". In Kulikov, Leonid; Lavidas, Nikolaos (eds.). *Proto-Indo-European Syntax and its Development*. John Benjamins.

1. **[^](#cite_ref-lehmann_53-0)** [Lehmann, Winfred P.](/source/Winfred_P._Lehmann) (1974). "Syntactic Developments from PIE to the Dialects". [*Proto-Indo-European Syntax*](https://liberalarts.utexas.edu/lrc/resources/books/pies/7-developments.php). University of Texas Press. [ISBN](/source/ISBN_(identifier)) [9780292733411](https://en.wikipedia.org/wiki/Special:BookSources/9780292733411).

1. **[^](#cite_ref-ringe_54-0)** Ringe, Donald (2006). *Proto-Indo-European to Proto-Germanic*. Oxford University Press.

1. **[^](#cite_ref-friedrich_55-0)** [Friedrich, Paul](/source/Paul_Friedrich_(linguist)) (1975). "Proto-Indo-European Syntax". *Journal of Indo-European Studies*. **1** (1). University of Chicago Press. [ISBN](/source/ISBN_(identifier)) [0-941694-25-9](https://en.wikipedia.org/wiki/Special:BookSources/0-941694-25-9).

## Bibliography

- Clackson, James (18 October 2007). [*Indo-European Linguistics: An Introduction*](https://www.cambridge.org/core/product/identifier/9780511808616/type/book). Cambridge University Press. [doi](/source/Doi_(identifier)):[10.1017/cbo9780511808616](https://doi.org/10.1017%2Fcbo9780511808616). [ISBN](/source/ISBN_(identifier)) [978-0-521-65367-1](https://en.wikipedia.org/wiki/Special:BookSources/978-0-521-65367-1).

- [Meier-Brügger, Michael](/source/Meier-Br%C3%BCgger) (2003), *Indo-European Linguistics*, New York: De Gruyter, [ISBN](/source/ISBN_(identifier)) [3-110-17433-2](https://en.wikipedia.org/wiki/Special:BookSources/3-110-17433-2)

- Szemerenyi, Oswald J. L. (13 February 1997). [*Introduction to Indo-European Linguistics*](https://academic.oup.com/book/48334). Oxford University Press. [doi](/source/Doi_(identifier)):[10.1093/oso/9780198240150.001.0001](https://doi.org/10.1093%2Foso%2F9780198240150.001.0001). [ISBN](/source/ISBN_(identifier)) [978-1-383-01320-7](https://en.wikipedia.org/wiki/Special:BookSources/978-1-383-01320-7).

- Kümmel, Martin Joachim (2022). ["Voiceless high vowels and syncope in older Indo-European"](https://www.italian-journal-linguistics.com/app/uploads/2021/05/9_Kuemmel.pdf) (PDF). *Italian Journal of Linguistics*. **32** (1): 175–190. [doi](/source/Doi_(identifier)):[10.26346/1120-2726-153](https://doi.org/10.26346%2F1120-2726-153).

- Kümmel, Martin Joachim. ["Uvular Stops or a Glottal Fricative? Theory and Data in Recent Reconstructions of PIE "Laryngeals""](https://archive.org/download/kummelljubljana2019.pdf_202011/k%C3%BCmmelljubljana2019.pdf.pdf) (PDF). *Seminar für Indogermanistik*.

- Klein, Jared; Joseph, Brian; Fritz, Matthias, eds. (2017). *Handbook of Comparative and Historical Indo-European Linguistics*. Vol. 1. De Gruyter Mouton. [doi](/source/Doi_(identifier)):[10.1515/9783110261288](https://doi.org/10.1515%2F9783110261288). [ISBN](/source/ISBN_(identifier)) [978-3-110-26128-8](https://en.wikipedia.org/wiki/Special:BookSources/978-3-110-26128-8).

- Klein, Jared; Joseph, Brian; Fritz, Matthias, eds. (2017). *Handbook of Comparative and Historical Indo-European Linguistics*. Vol. 2. De Gruyter Mouton. [doi](/source/Doi_(identifier)):[10.1515/9783110523874](https://doi.org/10.1515%2F9783110523874). [ISBN](/source/ISBN_(identifier)) [978-3-110-52387-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-110-52387-4).

- Klein, Jared; Joseph, Brian; Fritz, Matthias, eds. (2018). *Handbook of Comparative and Historical Indo-European Linguistics*. Vol. 3. De Gruyter Mouton. [doi](/source/Doi_(identifier)):[10.1515/9783110542431](https://doi.org/10.1515%2F9783110542431). [ISBN](/source/ISBN_(identifier)) [978-3-110-54243-1](https://en.wikipedia.org/wiki/Special:BookSources/978-3-110-54243-1).

## Further reading

- Spinney, Laura. *Proto: How One Ancient Language Went Global*. Bloomsbury Publishing (2026).

## External links

Wikimedia Commons has media related to [Proto-Indo-European language](https://commons.wikimedia.org/wiki/Category:Proto-Indo-European_language).

Look up ***[Appendix:Proto-Indo-European Swadesh list](https://en.wiktionary.org/wiki/Appendix:Proto-Indo-European_Swadesh_list)*** in Wiktionary, the free dictionary.

- Linguistic Research Center, [University of Texas at Austin](/source/University_of_Texas_at_Austin) - ["Indo-European Lexicon"](https://web.archive.org/web/20170728215921/http://liberalarts.utexas.edu/lrc/resources/books/index.php). Archived from [the original](http://liberalarts.utexas.edu/lrc/resources/books/index.php) on 28 July 2017. - ["Early Indo-European Online: Introduction to the Language Lessons"](https://lrc.la.utexas.edu/eieol). [Archived](https://web.archive.org/web/20251208124422/https://lrc.la.utexas.edu/eieol) from the original on 8 December 2025.

- ["Proto-Indo-European Lexicon"](http://pielexicon.hum.helsinki.fi/). Department of World Cultures, Department of Modern Languages, Indo-European Studies, [University of Helsinki](/source/University_of_Helsinki).

- ["Wheel and chariot in early IE: What exactly can we conclude from the linguistic data?"](https://archive.org/details/kummeleaa2019.pdf) (PDF). Department of Indo-European Linguistics, [University of Jena](/source/University_of_Jena).

- ["Indo-European Lexical Cognacy Database"](https://web.archive.org/web/20151107054612/http://ielex.mpi.nl/). Evolutionary Processes in Language and Culture, [Max Planck Institute for Psycholinguistics](/source/Max_Planck_Institute_for_Psycholinguistics). Archived from [the original](http://ielex.mpi.nl/) on 7 November 2015.

- ["Glottothèque: Ancient Indo-European Grammars"](https://spw.uni-goettingen.de/projects/aig/index.html). Linguistics Department, University of Göttingen. Video lectures on Ancient Indo-European languages

v t e Proto-Indo-European language Phonology Accent Centum and satem Glottalic theory Laryngeal theory s-mobile Sound laws asno law boukólos rule *kʷetwóres rule Bartholomae's Grassmann's Osthoff's Pinault's Siebs's Sievers's Stang's Szemerényi's Weise's Morphology Root Ablaut Thematic vowel Particles Verbs Copula h₂e-conjugation Aorist Present Nasal infix Narten presents Reduplicated presents *éye-presents *sḱé-presents Desideratives *ye-presents Nominals Adjectives Caland system Vṛddhi Pronouns Numerals Vocabulary Indogermanisches etymologisches Wörterbuch (IEW) Lexikon der indogermanischen Verben (LIV) Lexikon der indogermanischen Partikeln und Pronominalstämme (LIPP) Nomina im Indogermanischen Lexikon (NIL) Indo-European Etymological Dictionary (IEED) Artificial compositions Schleicher's fable The king and the god Homeland Kurgan hypothesis Schleicher theories Anatolian hypothesis Armenian hypothesis Outdated theories: Beech argument North European hypothesis Salmon problem See also Society Mythology Migrations Indo-European studies

Authority control databases International GND FAST National United States France BnF data Czech Republic Spain Sweden Israel Other IdRef Yale LUX

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Adapted from the Wikipedia article [Proto-Indo-European language](https://en.wikipedia.org/wiki/Proto-Indo-European_language) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Proto-Indo-European_language?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.