# Fidelity

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Quality of faithfulness or loyalty to another person or group

For other uses, see [Fidelity (disambiguation)](/source/Fidelity_(disambiguation)).

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[Palazzo Ducale in Venice](/source/Doge's_Palace%2C_Venice): [capital # 28](https://commons.wikimedia.org/wiki/Category:Capitals_in_the_Doge%27s_Palace_(Venice)_-_28) in the porch, featuring Virtues and vices — **In fidelitate nulli gero** (Fidelity)

**Fidelity** is the quality of [faithfulness](/source/Faithfulness) or [loyalty](/source/Loyalty). Its original meaning regarded [duty](/source/Duty) in a broader sense than the related concept of *[fealty](/source/Fealty)*. Both derive from the [Latin](/source/Latin) word *fidēlis*, meaning "faithful or loyal". In the [City of London](/source/City_of_London) financial markets it has traditionally been used in the sense encompassed in the motto "my word is my bond".

## In moral philosophy

In moral philosophy, fidelity refers to a person who keeps agreements. Strong fidelity refers to a person who keeps agreements even if not mutually beneficial to the other person.[1]

## Audio and electronics

See also: [Sound recording and reproduction](/source/Sound_recording_and_reproduction)

In audio, "fidelity" denotes how accurately a copy reproduces its source. In the 1950s, the terms "[high fidelity](/source/High_fidelity)" or "hi-fi" were popularized for equipment and recordings which exhibited more accurate [sound reproduction](/source/Sound_reproduction).[2] For example, a worn [gramophone record](/source/Gramophone_record) will have a lower fidelity than one in good condition, and a recording made by a low budget record company in the early 20th century is likely to have significantly less audio fidelity than a good modern recording.[3] Similarly in [electronics](/source/Electronics), fidelity refers to the correspondence of the output signal to the input signal, rather than sound quality, as in the popular internet connection technology "[Wi-Fi](/source/Wi-Fi)".[4]

The term "[lo-fi](/source/Lo-fi_music)" has existed since at least the 1950s, shortly after the acceptance of "hi-fi", but its definition evolved continuously between the 1970s and 2000s. In the 1976 edition of the *Oxford Dictionary*,[*[clarification needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify)*] lo-fi was added under the definition of "sound production less good in quality than '[hi-fi](/source/Hi-fi)'", and in the glossary of the 1977 book *The Tuning of the World*, was defined as "unfavourable signal-to-noise ratio". In 2003, the *Oxford Dictionary* added a second definition: "A genre of rock music characterized by minimal production, giving a raw and unsophisticated sound." A third was added in 2008: "Unpolished, amateurish, or technologically unsophisticated, esp. as a deliberate aesthetic choice."[5][6]

## Scientific modelling and simulation

In the fields of [scientific modelling](/source/Scientific_modelling) and [simulation](/source/Simulation), fidelity refers to the degree to which a model or simulation reproduces the state and behaviour of a real world object, feature or condition. Fidelity is therefore a measure of the realism of a model or simulation.[7] Simulation fidelity has also been described in the past as "degree of similarity".[8] In quantum mechanics and optics,[9] the fidelity of a field is calculated as an [overlap integral](/source/Orbital_overlap) of the field of interest with a reference or target field.

## Program evaluation

In the field of [program evaluation](/source/Program_evaluation), the term fidelity denotes how closely a set of procedures were implemented as they were supposed to have been. For example, it is difficult to draw conclusions from a study about formative assessment in school classrooms if the teachers are not able or willing to follow the procedures they received in training.[10]

## Translation

Main article: [Translation § Fidelity and transparency](/source/Translation#Fidelity_and_transparency)

In [translation](/source/Translation), *fidelity* is the extent to which a translation accurately renders the [meaning](/source/Meaning_(linguistics)) of the source text, without distortion. It is contrasted with *transparency*, which is the extent to which a translation appears to a native speaker of the target language to have originally been written in that language.

## See also

Wikiquote has quotations related to ***[Fidelity](https://en.wikiquote.org/wiki/Special:Search/Fidelity)***.

- [Classism](/source/Classism) – Discrimination on the basis of social classPages displaying short descriptions of redirect targets

- [Erikson's theory of personality](/source/Erik_Erikson#Erikson's_theory_of_personality) – Erikson's fidelity is the ability to commit to others and acceptance of others

- [Infidelity](/source/Infidelity) – Cheating, adultery, or having an affair

- [Knighthood](/source/Knighthood) – Honorary title awarded for service to a state or churchPages displaying short descriptions of redirect targets

- [Monasticism](/source/Monasticism) – Religious way of life

- [Rankism](/source/Rankism) – Rank-based discrimination

## References

1. **[^](#cite_ref-1)** Kuhn, Steven T. (1996). ["Agreement Keeping and Indirect Moral Theory"](https://www.jstor.org/stable/2940872). *The Journal of Philosophy*. **93** (3): 105–128. [doi](/source/Doi_(identifier)):[10.2307/2940872](https://doi.org/10.2307%2F2940872). [ISSN](/source/ISSN_(identifier)) [0022-362X](https://search.worldcat.org/issn/0022-362X).

1. **[^](#cite_ref-2)** Hartley, H. A. (1958). [*Audio Design Handbook*](https://web.archive.org/web/20090127021505/http://www.tech-systems-labs.com/books/hartley.pdf) (PDF). New York, New York: Gernsback Library. pp. 7, 20. [Library of Congress](/source/Library_of_Congress) Catalog Card No. 57-9007. Archived from [the original](http://www.tech-systems-labs.com/books/hartley.pdf) (PDF) on 2009-01-27. Retrieved 2009-08-08.

1. **[^](#cite_ref-3)** ["The Evolution of Microphone Technology: From Ribbon to Condenser"](https://www.newyorkaudioinstitute.com/blog/the-evolution-of-microphone-technology-from-ribbon-to-condenser). *New York Audio Institute*. Retrieved 2026-02-18.

1. **[^](#cite_ref-4)** ["fidelity – ATIS Telecom Glossary"](https://glossary.atis.org/glossary/fidelity/). Retrieved 2026-02-18.

1. **[^](#cite_ref-5)** Harper, Adam (2014). [*Lo-Fi Aesthetics in Popular Music Discourse*](https://ora.ox.ac.uk/objects/uuid:cc84039c-3d30-484e-84b4-8535ba4a54f8/datastreams/THESIS01) (PDF). [Wadham College](/source/Wadham_College). pp. 7–11. Retrieved March 10, 2018.

1. **[^](#cite_ref-6)** ["COMES WITH FRIES | What Does Lo-fi Actually Mean?"](https://www.comeswithfries.com/post/what-does-lo-fi-actually-mean). *www.comeswithfries.com*. Retrieved 2026-02-18.

1. **[^](#cite_ref-SISO_7-0)** ["SISO-REF-002-1999: Fidelity Implementation Study Group Report"](http://www.sisostds.org/ProductsPublications/ReferenceDocuments.aspx). Simulation Interoperability Standards Organization. 1999. Retrieved January 2, 2015.

1. **[^](#cite_ref-HaysSinger_8-0)** Hays, R. T.; Singer, M. J. (1989). *Simulation fidelity in training system design: Bridging the gap between reality and training*. Springer-Verlag.

1. **[^](#cite_ref-9)** Bowman, D.; Harte, T. L.; Chardonnet, V.; Groot, C. De; Denny, S. J.; Goc, G. Le; Anderson, M.; Ireland, P.; Cassettari, D. (2017-05-15). ["High-fidelity phase and amplitude control of phase-only computer generated holograms using conjugate gradient minimisation"](https://www.osapublishing.org/abstract.cfm?uri=oe-25-10-11692). *Optics Express*. **25** (10): 11692–11700. [arXiv](/source/ArXiv_(identifier)):[1701.08620](https://arxiv.org/abs/1701.08620). [Bibcode](/source/Bibcode_(identifier)):[2017OExpr..2511692B](https://ui.adsabs.harvard.edu/abs/2017OExpr..2511692B). [doi](/source/Doi_(identifier)):[10.1364/OE.25.011692](https://doi.org/10.1364%2FOE.25.011692). [ISSN](/source/ISSN_(identifier)) [1094-4087](https://search.worldcat.org/issn/1094-4087). [PMID](/source/PMID_(identifier)) [28788742](https://pubmed.ncbi.nlm.nih.gov/28788742).

1. **[^](#cite_ref-ODonnell_10-0)** O'Donnell, Carol L. (2008). "Defining, Conceptualizing, and Measuring Fidelity of Implementation and Its Relationship to Outcomes in K–12 Curriculum Intervention Research". *Review of Educational Research*. **78** (1): 33–84. [doi](/source/Doi_(identifier)):[10.3102/0034654307313793](https://doi.org/10.3102%2F0034654307313793).

v t e Virtues About virtues Endowment Moral character Nicomachean Ethics Positive psychology Trait theory Virtue ethics Virtue families Bodhipakkhiyā dhammā Brahmavihārās Bushidō Catalogue of Vices and Virtues Civic virtue Emi Omo Eso Epistemic virtues Five virtues Four Cardinal Principles and Eight Virtues Intellectual virtues Moral virtues Nine Noble Virtues Omoluwabi Pāramīs Prussian virtues Scout Law Seven virtues Cardinal Theological Teachings of the Seven Grandfathers Three Treasures Values in Action Inventory of Strengths Yamas Individual virtues Accountability Alertness Altruism Authenticity Calmness Charisma Charity Chastity Chivalry Cleanliness Compassion Conscientiousness Courage Civil Moral Courtesy Diligence Discernment Discipline Duty Empathy Endurance Equanimity Etiquette Faith Faithfulness Fidelity Foresight Forgiveness Frugality Generosity Gentleness Glory Good faith Gratitude Heroism Honesty Honour Hope Hospitality Humanity Humility Impartiality Innocence Insight Integrity Intelligence Emotional Social Judgement Justice Kindness Love Loyalty Magnanimity Magnificence Meekness Mercy Moderation Modesty Nonattachment Patience Patriotism Perspicacity Philanthropy Piety Filial Pity Politeness Prudence Punctuality Religion Renunciation Resilience Respect Reverence Righteous indignation Righteousness Self-control Self-cultivation Self-transcendence Simplicity Sincerity Solidarity Sportsmanship Sympathy Taste Temperance Tranquillity Trust Wisdom Wit Workmanship Chinese De Jing Li Ren Yi Greek Agape Arete Ataraxia Eutrapelia Philotimo Phronesis Sophia Sophrosyne Indian Adhiṭṭhāna Ahimsa Akrodha Aparigraha Ārjava Asteya Brahmacharya Dāna Dhṛti Hrī Karuṇā Kshama Kshanti Mettā Muditā Nishkama Karma Prajñā Samatva Satya Shaucha Sevā Śraddhā/Saddhā Upekṣā Vīrya Latin Auctoritas Caritas Decorum Dignitas Fides Gravitas Humanitas Pietas Virtus Other Ganbaru Giri Sadaqah Seny Sisu Virtù Category

Authority control databases GND

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