verb (used with object), dec·i·mat·ed, dec·i·mat·ing.
- to destroy a great number or proportion of: The population was decimated by a plague.
- to select by lot and kill every tenth person of.
- Obsolete. to take a tenth of or from.
- to destroy or kill a large proportion ofa plague decimated the population
- (esp in the ancient Roman army) to kill every tenth man of (a mutinous section)
c.1600, in reference to the practice of punishing mutinous military units by capital execution of one in every 10, by lot; from Latin decimatus, past participle of decimare (see decimation). Killing one in ten, chosen by lots, from a rebellious city or a mutinous army was a common punishment in classical times. The word has been used (incorrectly, to the irritation of pedants) since 1660s for “destroy a large portion of.” Related: Decimated; decimating.