Nouns

(n)informer, betrayer, rat, squealer, blabberone who reveals confidential information to the police or other authority

Verbs

(v)chatter, piffle, palaver, prate, tittle-tattle, twaddle, clack, maunder, prattle, blab, gibber, tattle, blabber, gabblespeak (about unimportant matters) rapidly and incessantly