verb
1.
Synonyms: deceive , beguile, bluff, delude, double-cross, humbug, illude, juggle, mislead, take in
Related Word: ensnare, entrap, snare, trap
2.
to prove faithless or treacherous
betrayed his own people by going over to the enemy
Synonyms: cross, double-cross, sell, sell out, ||split
Related Word: desert, renegade; give away, inform, turn in; collaborate; apostatize
Idioms: act ( or play) the traitor, break faith, round on, sell down the river
3.
Synonyms: reveal 1, blab (out), disclose, discover, divulge, give away, spill, tell, uncover, unveil
Related Word: demonstrate, evidence, evince, manifest, show; betoken, indicate
Contrasted words: defend, guard, protect, safeguard, shield