BETRAY, be disloyal to, be unfaithful to, desert, break one's promise to, double-cross, break faith with, sell out, play false, inform on/against; informal tell on, sell down the river, squeal on, stitch up, peach on, do the dirty on; Brit. informal grass on, shop; N. Amer. informal rat out, finger, drop a/the dime on; Austral. informal pimp on, pool, put someone's pot on.
2192; headword