(transitive) To multiply by two. / (intransitive) To increase by 100%, to become twice as large in size. / To be the double of; to exceed by twofold; to contain or be worth twice as much as.

Twice over; twofold; doubly. / Two together; two at a time. (especially in see double)

Twice the number, amount, size, etc. / A person who resembles and stands in for another person, often for safety purposes / A drink with two portions of alcohol.

Made up of two matching or complementary elements. / Of twice the quantity. / Of a family relationship, related on both the maternal and paternal sides of a family. / Designed for two users.

simple past tense and past participle of double

(idiomatic) Rapidly or immediately.

(military) In double time. / (soccer) scoring a brace

The process or an instance of making something double; a multiplication by two. [from 14th c.] / The act of turning around, or doubling back. [from 16th c.] / A pleat or fold. [from 17th c.]

present participle of double

The state of being double or doubled. / Behaviour intended to deceive people.