OXFORD DICTIONARY
, adj., n., & v.
--adj.
1 fourfold.
2 a having four parts. b involving four participants (quadruple alliance).
3 being four times as many or as much.
4 (of time in music) having four beats in a bar.
--n. a fourfold number or amount.
--v.tr. & intr. multiply by four; increase fourfold.
quadruply adv.
F f. L quadruplus (as QUADRI-, -plus as in duplus DUPLE)
ROGET THESAURUS
Quadruplication
N
quadruplication, fourfold, four times, quadrable, quadrumanous,
quadruple, quadruplicate, quadrible, fourth, quadrifoliate, quadrifoliolate, quadrigeminal, quadrigeminate, quadriplanar, quadriserial, four times, in the fourth place, fourthly.