1.  betrayer(n = noun.person) blabber, informer, rat, squealer - one who reveals confidential information in return for money;
is a kind of informant, source
has particulars: canary, fink, sneak, sneaker, snitch, snitcher, stool pigeon, stoolie, stoolpigeon, copper's nark, nark, grass, supergrass
Derived forms verb betray₅, verb betray₂

2.  betrayer(n = noun.person) double-crosser, double-dealer, traitor, two-timer - a person who says one thing and does another;
is a kind of beguiler, cheat, cheater, deceiver, slicker, trickster
has particulars: judas
Derived form verb betray₆

   One who, or that which, betrays. [1913 Webster]

N  knave, rogue, Scapin, rascal, Lazarillo de Tormes, bad man, blackguard, barrater, barrator, shyster, traitor, betrayer, archtraitor, conspirator, Judas, Catiline, reptile, serpent, snake in the grass, wolf in sheep's clothing, sneak, Jerry Sneak, squealer, tell-tale, mischief-maker, trimmer, fence-sitter, renegade, truant, recreant, sycophant.