betray (v.)
late 13c., bitrayen "mislead, deceive, betray," from be- + obsolete Middle English tray, from Old French traine "betrayal, deception, deceit," from trair (Modern French trahir) "betray, deceive," from Latin tradere "hand over," from trans- "across" (see trans-) + dare "to give" (see date (n.1)). Related: Betrayed; betraying.