1. (v. t.) To double again or repeatedly; to increase by continued or repeated additions; to augment greatly; to multiply.

2. (v. i.) To become greatly or repeatedly increased; to be multiplied; to be greatly augmented; as, the noise redoubles.

accelerate aggravate beef up blow up come again complicate concentrate condense consolidate copy deepen ditto do a repeat do again do over double dupe duplicate echo enhance exacerbate exaggerate geminate heat up heighten hop up hot up imitate ingeminate intensify jazz up key up magnify make complex mount multiply by two parrot plagiarize quote ramify redo reduplicate reecho regurgitate reincarnate reinforce renew repeat replicate reproduce revive rise rouse say again sharpen soup up step up strengthen triple twin whet