'Decimation' definitions:

Definition of 'decimation'

From: WordNet
noun
Destroying or killing a large part of the population (literally every tenth person as chosen by lot)

Definition of 'Decimation'

From: GCIDE
  • Decimation \Dec`i*ma"tion\, n. [L. decimatio: cf. F. d['e]cimation.]
  • 1. A tithing. [Obs.] --State Trials (1630). [1913 Webster]
  • 2. A selection of every tenth person by lot, as for punishment. --Shak. [1913 Webster]
  • 3. The destruction of any large proportion, as of people by pestilence or war. --Milman. [1913 Webster]