a piece placed at or forming the mouth, as of a receptacle or tube.

a piece or part, as of an instrument, to which the mouth is applied or which is held in the mouth

the mouthpiece of a trumpet.

the part of a bit or bridle, as for a horse, that passes through the animal's mouth.

a person, newspaper, etc., that conveys the opinions or sentiments of others; spokesperson.

Slang . a lawyer, esp. a criminal lawyer.

noun

agent , delegate , pr person , representative , speaker , spokesman , spokeswoman , mouth , spokesperson , adviser , attorney , counselor , embouchure , lawyer