the act or an instance of killing a number of usually helpless or unresisting human beings under circumstances of atrocity or cruelty witnessed the massacre of a boatload of refugees 2 : a cruel or wanton (see 1wanton 3a) murder 3 : a wholesale slaughter of animals Residents engaged in a citywide cat massacre. 4 : an act of complete destruction the author's massacre of traditional federalist presuppositions — R. G. McCloskey the Puritan massacre of statues and pictures — Robert Hughes