Double

Double is a term used to denote twofold or two identical parts. It originates from the Latin duplex and is used as an adjective for items consisting of two parts or copies, as a noun to denote a duplicate or copy, and as a verb meaning to make twofold or to duplicate.

In mathematics and measurement, doubling a quantity means multiplying it by two. In everyday language, the term conveys the idea of two of something or a counterpart that mirrors another.

In computing and programming, double refers to a data type known as a double or double precision, typically a 64-bit floating-point representation that stores real numbers with a wide range and precision. Many languages, including C and Java, use the keyword double for this type, while SQL and related systems often provide a DOUBLE or DOUBLE PRECISION type.

In sports, a double has specific meanings. In baseball, a double is a hit that allows the batter to reach second base. In tennis and badminton, doubles describe competition between teams of two players. In bowling, a double is two consecutive strikes recorded across two frames.

In film and entertainment, a double can be a stunt double, who stands in for an actor for dangerous or complex scenes, or a body double, a stand-in used for lighting, positioning, or reshoots. In literature and psychology, the concept of a double or doppelgänger refers to a look-alike or mirrored counterpart of a character.

Other uses include duplication in copying processes, and musical terms such as double stops, where two notes are played simultaneously on a string instrument.