A person who routinely inhales and exhales through the mouth, instead of through the nose. / (idiomatic, slang, derogatory) A person who is boorish, stupid, or otherwise unattractive.

plural of motor mouth

foot-and-mouth disease

(intransitive, slang) To complain or otherwise express oneself in a loud, immoderate manner. / (transitive, intransitive, slang) To talk impudently, especially to one's superior.

present participle of mouth off

Third-person singular simple present indicative form of mouth off

Alternative spelling of mouth breather

(idiomatic, used in similes) An indistinct, muffled or garbled manner of speaking.

(idiomatic, euphemistic) The characteristic of regularly using vulgar language, especially strong profanities. / (idiomatic) A person having this characteristic.

plural of horse's mouth