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 mouth organ

That part of a river, estuary or lagoon which broadens out as it meets the sea

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.

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

(informal) Regularly using vulgar language, especially strong profanities.

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

simple past tense and past participle of mouth off

present participle of mouth off