com·pur·ga·tor \ˈkäm(ˌ)pərˌgād.ər\noun (-s) Etymology: Medieval Latin, from Latin compurgatus + -or : one that defends or supports another < spoke most kindly as my compurgators — H.J.Laski > specifically: one that under oath vouches for the blameless character or conduct of an accused person attempting thereby to vindicate him