mouthpiece

noun

1. A part of any device that functions in or near the mouth, especially:

   “"It's 'Soapy,' talking from somewhere down there," rapped out Nickle, covering the mouthpiece as he spoke back into the room. "Get Joolby if you can, one of you."”

2. A part of any device that functions in or near the mouth, especially:
3. A mouthguard.
4. (broadly)A spokesman; one who speaks on behalf of someone else.

   “The novel's protagonist serves as a mouthpiece for the author's political views.”

   “Seeming “real” has been the aim since the earliest police procedurals, which began a long tradition of Hollywood productions acting as a mouthpiece for police departments.”

   “Xi Jinping has told the People’s Liberation Army to “focus all its energy on fighting” in preparation for war, a Chinese Communist party mouthpiece has reported.”

   “Rightwing media mouthpieces and ICE get both barrels in South Park’s latest zeitgeist-capturing satire.”

5. (slang)A lawyer for the defense.