Regulier

Regulier is an adjective used in French and other languages to denote something that follows a rule, is ordinary, or recurs at fixed intervals. In French, the masculine singular form is régulier and the feminine form is régulière; plural forms are réguliers and régulières. It can describe schedules, habits, rhythms, patterns, or standards, such as un horaire régulier (a regular schedule) or une démarche régulière (a regular approach).

Etymology traces the word to Latin regularis, via Old French regulier or régulier, related to regula, meaning rule or standard. The sense of conformity to a rule or a standard is central to its use across many domains.

In grammar, the term appears in the distinction between verb groups: les verbes réguliers, whose conjugations follow predictable patterns, and les verbes irréguliers, which do not. In mathematics and geometry, régulier is used in several related ways. A polygone régulier is a polygon with equal sides and angles. In French mathematics, the phrase fonction régulière designates a well-behaved function, often meaning one that can be locally expressed as a ratio of polynomials; in algebraic geometry this corresponds to a regular function on a variety. The term can also describe consistent phenomena, such as a régulier tempo in music or sleep that is kept on a predictable schedule.

Beyond French, Dutch uses regulier with a similar meaning. In English, regulatory or normal equivalents are preferred, and regulier appears mainly in loan translations, specialized technical contexts, or as a surname or place name.