Definition of decimates:
(v) :
(loosely) To devastate: to reduce or destroy significantly but not completely.
(v) :
To destroy or remove one-tenth of (something).
(v) :
(proscribed) To reduce to one-tenth: to destroy or remove nine-tenths of (something).
(v) :
(computer graphics) To replace (a high-resolution model) with another of lower but acceptable quality. (Usually algorithmically)
(v) :
(archaic) To kill one-tenth of (a group), (historical, specifically) as a military punishment in the Roman army selected by lot, usually carried out by the surviving soldiers.
(n) :
A tithe or other 10% tax or payment.