A phrase that has two meanings, especially where one is innocent and literal, the other risqué, bawdy, or ironic; an innuendo.

Used other than figuratively or idiomatically: see double, barrelled. Having two barrels, as a gun. / Twofold, having a double purpose or nature.

(chemistry) a reaction between two substances in which two parts of each substance are exchanged; metathesis

two pairs of railway switches forming two connections that cross over between two parallel tracks

(film, television) A type of body double: a skilled stand-in used for dangerous film or video sequences such as jumping out of a building, leaping from vehicle to vehicle, and fight sequences.

An action which is intended to be perceived as a bluff, but which is not.

(idiomatic) Of a single resource, reserved for two different users at the same time.

A Weymouth bridle, which uses both a bradoon, held by a sliphead, and a curb bit, and is used with two reins.

A challenge that is harder or naughtier than a regular dare

To challenge with a double dare.