verb-intransitive. To bark sharply or shrilly; yelp.verb-intransitive. Slang To talk noisily or stupidly; jabber.v. To utter by yapping.n. A sharp, shrill bark; a yelp.n. Slang Noisy, stupid talk; jabber.n. Slang The mouth: Shut your yap. n. Slang A stupid, crude, or loud person.