fourfold; consisting of four parts

a quadruple alliance.

four times as great.

Music . having four beats to a measure.

a number, amount, etc., four times as great as another.

something, as a series of acrobatic somersaults, made up of four clearly defined parts or stages

the first trapeze artist to perform a quadruple successfully.

to make or become four times as great

To serve 24 people, quadruple the recipe. My savings quadrupled in 20 years.