mouthpiece noun

1 part of a telephone

ADJ. phone/telephone

VERB + MOUTHPIECE cover (up), put your hand over He put his hand over the mouthpiece and called his wife to the phone.

2 sb/sth that informs the public about sb/sth's opinions

ADJ. official, political

VERB + MOUTHPIECE act as, be

PREP. ~ for/of The media is controlled by the state and acts as a mouthpiece for the ruling party.