From WordNet (r) 3.0 (2006):
blab
v 1: divulge confidential information or secrets; "Be careful--
his secretary talks" [syn: spill the beans, let the cat
out of the bag, talk, tattle, blab, peach,
babble, sing, babble out, blab out] [ant: keep
one's mouth shut, keep quiet, shut one's mouth]
2: speak (about unimportant matters) rapidly and incessantly
[syn: chatter, piffle, palaver, prate, tittle-
tattle, twaddle, clack, maunder, prattle, blab,
gibber, tattle, blabber, gabble]