10 letters · 15 points in Scrabble
noun destroying or killing a large part of the population (literally every tenth person as chosen by lot)
originBorrowed from Latin decimātiō, a punishment where every 10th man in a unit would be stoned to death by the men who were spared. Used by the Romans to keep order in their military. Compare septimation and vicesimation.
Etymology from Wiktionary, CC BY-SA 3.0