Synonyms for Slaughter (same or very similar meaning)
WordNet sense 1 (a sound defeat):
debacle, drubbing, thrashing, walloping, whipping, trouncingWordNet sense 2 (kill (animals) usually for food consumption):
butcherWordNet sense 3 (kill a large number of people indiscriminately):
massacre, mow downWordNet sense 4 (the savage and excessive killing of many people):
butchery, carnage, carnage, mass murderFrom the ODE community, based on WordNetadd/edit