triple

Triple is a word denoting threefold or something composed of three parts. As a noun, it can refer to a group, set, or instance of three; as an adjective, it describes something that comes in threes or is three times as large; as a verb, to triple means to multiply by three or to increase threefold. The word derives from the Latin triplex meaning "threefold," from tres "three" and plicare "to fold."

In mathematics, a triple is a 3-tuple, an ordered triple of elements written as (a, b, c). It is a basic data structure for storing three related values. In vector algebra, the scalar triple product a · (b × c) yields a signed volume, and triple integrals ∭ extend integration to three dimensions. In chemistry, a triple bond is formed by three shared electron pairs, as in nitrogen gas (N2).

In thermodynamics, the triple point is the unique combination of temperature and pressure at which a substance can exist in solid, liquid, and gas phases simultaneously.

In music, triple relates to triple meter, a time signature with three beats per measure, and to triplets, groups of three notes played in the time of two. In sports, a triple is a base hit that allows the batter to reach third base, notably in baseball.

As a verb, to triple means to increase threefold: "the population tripled in a decade."