WordNet (r) 3.0 (2006):

gabby
    adj 1: full of trivial conversation; "kept from her housework by
           gabby neighbors" [syn: chatty, gabby, garrulous,
           loquacious, talkative, talky]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "gabby":
   all jaw, candid, chatty, communicative, conversational, effusive,
   expansive, flip, fluent, frank, garrulous, gassy, glib, gossipy,
   gregarious, gushy, long-winded, loose-tongued, loquacious,
   multiloquent, multiloquious, newsy, overtalkative, prolix, smooth,
   sociable, talkative, talky, verbose, voluble, windy