decimate (v.)

To decimate a group is to kill or destroy a large part of it. The word holds a more exact number from an older use: ten.¹

The Latin decimare meant to punish every tenth person. Accounts of Roman military discipline describe soldiers chosen by lot, one in ten, from a disgraced unit and put to death.¹²

That does not mean Roman commanders routinely killed a tenth of their men. The evidence for its use in the Republic is sparse, and a study of the practice argues that it was revived in the late Republic after long periods without it.²

Today decimate usually means to devastate, even when the loss is much more than ten percent. The tenth remains in the word, though it is no longer a rule for using it.¹

The disease decimated the herd.