käyrä

Käyrää is the partitive singular form of the Finnish noun käyrä, which means curve, bend, or arc. The basic sense is a line or edge that deviates from a straight path, described in mathematics, geometry, geography, and everyday language. The form käyrää is used when the curve is the indefinite object of a verb or when an unspecified amount of curve is being referred to.

In mathematics and related disciplines, käyrä denotes a curve, which can be a straight line as well as any non-straight path traced by a point or function. Common contexts include descriptions of geometric or analytic curves, such as parametric curves (parametrinen käyrä) or other types of continuous mappings. In calculus and algebra, phrases may describe properties of a käyrä, such as curvature or intersections with other objects.

In everyday language and cartography, käyrä also appears to describe any curved feature, such as a road bend or contour on a map. On topographic maps, contour lines may be referred to as käyriä viivoja, highlighting their curved nature rather than a strictly straight form.

Grammatically, käyrä behaves like a standard Finnish noun: its nominative singular is käyrä, its partitive singular is käyrää, and its plural forms include käyrät (nominative) and käyriä (partitive). The word is widely understood in Finnish linguistic and technical contexts as a general term for curved shapes and lines.