The body opening through which an animal takes in food. The cavity lying at the upper end of the alimentary canal, bounded on the outside by the lips and inside by the oropharynx and containing in higher vertebrates the tongue, gums, and teeth. This cavity regarded as the source of sounds and speech. The opening to any cavity or canal in an organ or a bodily part. The part of the lips visible on the human face. A person viewed as a consumer of food: has three mouths to feed at home. A pout, grimace, or similar expression. Utterance; voice: gave mouth to her doubts. A tendency to talk excessively or unwisely. Impudent or vulgar talk: Watch your mouth. A spokesperson: a mouthpiece. A natural opening, as the part of a stream or river that empties into a larger body of water or the entrance to a harbor, canyon, valley, or cave. The opening through which a container is filled or emptied. The opening between the jaws of a vise or other holding or gripping tool. Music An opening in the pipe of an organ. Music The opening in the mouthpiece of a flute across which the player blows. To speak or pronounce, especially: To declare in a pompous manner; declaim: mouthing his opinions of the candidates. To utter without conviction or understanding: mouthing empty compliments. To form soundlessly: I mouthed the words as the others sang. To utter indistinctly; mumble. To take or move around in the mouth. To orate affectedly; declaim. To grimace. mouth off Slang To express one's opinions or complaints in a loud, indiscreet manner.