régulier

Régulier is a French adjective used to describe what follows a rule, order, or pattern, or what occurs at steady intervals. It can also mean ordinary, normal, or consistent. The feminine form is régulière, and the plural forms are réguliers (masculine) and régulières (feminine). As a noun, régulier exists but is less common and may refer to a person or thing acting with regularity, for example a regular customer or a pedestrian who is a regular.

Etymology and related forms: the word comes from the Latin regulus, a diminutive of regula (rule), via the French verb réguler. Related nouns include régularité (regularity) and adverbs such as régulièrement (regularly).

In language and grammar, régulier is widely used to distinguish categories of words and constructions. A verbe régulier is a verb whose conjugation follows a standard pattern (for example aimer, finir), contrasted with verbe irrégulier (aller, venir). In everyday use, one speaks of un emploi régulier, un horaire régulier, or une vie régulière to denote routine and stability.

In mathematics and science, régulier signals the idea of regularity or smoothness depending on context. In mathematics, a fonction régulière in algebraic geometry refers to a function well defined on an object, often expressible locally by polynomials; in differential topology and related fields, regular points or regular values denote non-singular or well-behaved places of a map. In general discourse, régulier frequently appears in phrases describing cadence, scheduling, or behavior that is dependable and consistent.

See also: régularité, régulariser, irrégulier, regularité in mathematics and linguistics.