1 bark, yelp:
Their dog was yapping away all night.
2 gabble, babble, blither or blather, chatter, jabber, tattle, prattle, prate, Colloq chiefly Brit witter, natter, Slang jaw, run on, US run off at the mouth:
I wish she'd stop her yapping and give me some peace.
3 mouth, Slang trap, gob, US bazoo:
If only Sam would shut his big yap once in a while!