Courant

Courant is a word from the French language with both general and technical uses. As an adjective, it means current or flowing, and by extension modern or up-to-date when referring to what is happening now. As a noun, courant can denote a flow or stream of liquid or air, and figuratively a prevailing tendency or movement. In physics and engineering it appears in compound terms such as courant électrique (electric current), courant alternatif (alternating current), and courant continu (direct current). It also describes a weather or air movement, for example un courant d'air, and a current of opinion, such as un courant d'opinion.

In English-language contexts, courant is most commonly encountered in proper nouns and technical phrases rather than as a general vocabulary word. The surname Courant is notable for mathematician Richard Courant (1888–1972), whose work helped shape modern analysis. The Courant Institute of Mathematical Sciences at New York University bears his name. In numerical analysis, the Courant–Friedrichs–Lewy condition, or CFL condition, is a fundamental stability criterion for the discretization of partial differential equations. The term thus appears primarily in mathematical and scientific contexts as a surname or in borrowed phrases, rather than as part of everyday English usage.