noun

• (anatomy) The front opening of a creature through which food is ingested.
  ""Open your mouth and say 'aah'," directed the doctor."
• (slang) A loud or overly talkative person.
  "My kid sister is a real mouth; she never shuts up."
• (slang) A gossip.
  "Siobhán, you know Donna's a mouth."
• (saddlery) The crosspiece of a bridle bit, which enters the mouth of an animal.

verb

• (transitive) To speak; to utter.
  "He mouthed his opinions on the subject at the meeting."
• (transitive) To represent (words or sounds) by making the actions of speech, but silently, without producing sound; to frame.
  "The prompter mouthed the words to the actor, who had forgotten them."
• (transitive, intransitive) To move the mouth, with or without sound; to form (air or words) with the mouth, with or without sound.
  "But words are nothing to the misbelieving -- mere air mouthed into a sound."
• (ambitransitive) To utter with a voice that is overly loud or swelling.
  "Those who endeavor to become eloquent by mere imitation of some celebrated model—an actor for instance—often attempt to gain this quality by altering their voice in an unnatural manner. Such a process never produces any thing but mouthing."