Väli

Väli is a Finnish noun meaning the space between two objects, a gap, or a span. It can refer to a physical distance, a period of time, or a mathematical interval. The word is native to Finnish and is widely used in everyday language and in technical contexts.

In everyday use, väli denotes the space that separates things. Examples include kahden kaupungin välinen matka (the distance between two cities) and aikaväli (a time interval). The term also appears in compounds that express intervals or gaps, such as aikaväli.

In mathematics, väli denotes an interval on the real number line. The inclusive interval from a to b is written as väli [a, b], consisting of all x with a ≤ x ≤ b. Open and half-open intervals are written as [a, b), (a, b], etc. The concept also appears in higher-level terms such as väliarvo, meaning the intermediate value, and väliarvolause, the intermediate value theorem.

Etymology: Väli is a native Finnish word derived from Proto-Finnic *väli-, cognate with Estonian väli, meaning space or interval, reflecting its core sense of distance or separation.

See also: interval, aikaväli, väliarvo, gap.