Betrayer

Noun

 * 1) Someone who betrays, or reveals confidential information; a squealer or informer.
 * 2) A double-crosser.

Adjectives for Betrayer
accidental; circumspect; disloyal; shameless; subtle; treacherous; unwitting.

Verbs for Betrayer
accuse—; confront—; denounce—; dishonor—; execute—; vindicate—; —deserts; — discloses, —flees.

Thesaurus
archtraitor, blab, blabber, blabberer, blabbermouth, cockatrice, conniver, conspirator, conspirer, convict, criminal, crook, debaucher, deceiver, defiler, delator, desperado, desperate criminal, despoiler, double agent, double-crosser, double-dealer, felon, fink, fugitive, gallows bird, gangster, gaolbird, informer, intrigant, intriguer, jailbird, lawbreaker, machinator, mobster, narc, nark, outlaw, peacher, plotter, public enemy, quisling, racketeer, raper, rapist, rat, ravager, ravisher, schemer, scofflaw, seducer, serpent, snake, snitch, snitcher, spy, squealer, stool pigeon, stoolie, swindler, talebearer, tattler, tattletale, telltale, thief, thug, timeserver, traitor, treasonist, trimmer, turncoat, two-timer, violator, whistle-blower

Etymology
From.