{{Wiktionary|regular|regularity}} '''Regular''' and '''regularity''' may refer to: {{TOC right|limit=2}}
== Arts, entertainment, and media== ===Music=== * "Regular" (Badfinger song) * Regular tunings of stringed instruments, tunings with equal intervals between the paired notes of successive open strings
===Other uses=== * Regular character, a main character who appears more frequently and/or prominently than a recurring character * Regular division of the plane, a series of drawings by the Dutch artist M. C. Escher which began in 1936
== Language == * Regular inflection, the formation of derived forms such as plurals in ways that are typical for the language ** Regular verb * Regular script, the newest of the Chinese script styles
== Mathematics == === Algebra and number theory === * Regular category, a kind of category that has similarities to both Abelian categories and to the category of sets * Regular chains in computer algebra * Regular element (disambiguation), certain kinds of elements of an algebraic structure * Regular extension of fields * Regular ideal (multiple definitions) * Regular Lie group * Regular matrix (disambiguation) * Regular monomorphisms and regular epimorphisms, monomorphisms (resp. epimorphisms) which equalize (resp. coequalize) some parallel pair of morphisms * Regular numbers, numbers which evenly divide a power of 60 * Regular p-group, a concept capturing some of the more important properties of abelian ''p''-groups, but general enough to include most "small" ''p''-groups * Regular prime, a prime number ''p'' > 2 that does not divide the class number of the ''p''-th cyclotomic field * The regular representation of a group G, the linear representation afforded by the group action of G on itself * Regular ring, a ring such that all its localizations have Krull dimension equal to the minimal number of generators of the maximal ideal ** von Neumann regular ring, or absolutely flat ring (unrelated to the previous sense) * Regular semi-algebraic systems in computer algebra * Regular semigroup, related to the previous sense * *-regular semigroup
=== Analysis === * Borel regular measure * Cauchy-regular function (or Cauchy-continuous function,) a continuous function between metric spaces which preserves Cauchy sequences * Regular functions, functions that are analytic and single-valued (unique) in a given region * Regular measure, a measure for which every measurable set is "approximately open" and "approximately closed" * The regular part, of a Laurent series, the series of terms with positive powers * Regular singular points, in theory of ordinary differential equations where the growth of solutions is bounded by an algebraic function * Regularity, the degree of differentiability of a function * Regularity conditions arise in the study of first-class constraints in Hamiltonian mechanics * Regularity of an elliptic operator * Regularity theory of elliptic partial differential equations
=== Combinatorics, discrete math, and mathematical computer science === * Regular algebra, or Kleene algebra * Regular code, an algebraic code with a uniform distribution of distances between codewords * Regular expression, a type of pattern describing a set of strings in computer science * Regular graph, a graph such that all the degrees of the vertices are equal ** Szemerédi regularity lemma, some random behaviors in large graphs * Regular language, a formal language recognizable by a finite state automaton (related to the regular expression) * Regular map (graph theory), a symmetric tessellation of a closed surface * Regular matroid, a matroid which can be represented over any field * Regular paperfolding sequence, also known as the dragon curve sequence * Regular tree grammar
=== Geometry === * Castelnuovo–Mumford regularity of a coherent sheaf * Closed regular sets in solid modeling * Irregularity of a surface in algebraic geometry * Regular curves * Regular grid, a tesselation of Euclidean space by congruent bricks * Regular map (algebraic geometry), a map between varieties given by polynomials * Regular point, a non-singular point of an algebraic variety * Regular point of a differentiable map, a point at which a map is a submersion * Regular polygons, polygons with all sides and angles equal ** Regular polyhedron, a generalization of a regular polygon to higher dimensions **Regular polytope, a generalization of a regular polygon to higher dimensions * Regular skew polyhedron
=== Logic, set theory, and foundations === * Axiom of Regularity, also called the Axiom of Foundation, an axiom of set theory asserting the non-existence of certain infinite chains of sets * Partition regularity * Regular cardinal, a cardinal number that is equal to its cofinality * Regular modal logic
=== Probability and statistics === * Regular conditional probability, a concept that has developed to overcome certain difficulties in formally defining conditional probabilities for continuous probability distributions * Regular stochastic matrix, a stochastic matrix such that all the entries of some power of the matrix are positive
=== Topology === * Free regular set, a subset of a topological space that is acted upon disjointly under a given group action * Regular homotopy * Regular isotopy in knot theory, the equivalence relation of link diagrams that is generated by using the 2nd and 3rd Reidemeister moves only * Regular space (or <math>T_3</math>) space, a topological space in which a point and a closed set can be separated by neighborhoods
== Military == * Regular army, the official army of a state or country ** British Regulars, of the 18th and 19th centuries ** Regular Army (United States) ** Regular Force, of the Canadian Forces
== Organizations == * Regular Baptists, an 18th-century American and Canadian Baptist group * Regular clergy, members of a religious order subject to a rule of life * Regular Masonic jurisdictions, or ''regularity'', refers to the constitutional mechanism by which Freemasonry Grand Lodges or Grand Orients give one another mutual recognition
==People== * Moses Regular (born 1971), America football player
== Science and social science == * Regular economy, an economy characterized by an excess demand function whose slope at any equilibrium price vector is non-zero * Regular moon, a natural satellite that has low eccentricity and a relatively close and prograde orbit * Regular solutions in chemistry, solutions that diverge from the behavior of an ideal solution only moderately
== Other uses == * Regular bowel movements, the opposite of constipation * Regular customer, a person who frequently visits the same restaurant, pub, store, transit provider, etc. * Regular octane rating of gasoline, as a differentiation from "premium" and similar variants * Regular stance (or footedness) in boardsports, a stance in which the left foot leads (as compared to "goofy") * Regular type, referring to Roman type, an upright style of typeface or computer font, as compared to italic and blackletter * Presumption of regularity, a legal principle
==See also== *{{look from |regular}} *{{in title|regular}} * Irregular (disambiguation) * Regular set (disambiguation) * Quasiregular {{disambiguation}}