1. To take the tenth part of; to tithe.
2. To select by lot and punish with death every tenth man of; as, to decimate a regiment as a punishment for mutiny.
3. To destroy a considerable part of; as, to decimate an army in battle; to decimate a people by disease.
Origin: L. Decimatus, p. P. Of decimare to decimate (in senses 1 & 2), fr. Decimus tenth. See Decimal.