/ ˈmaʊθpiːs; NAmE / noun
1.
the part of the telephone that is next to your mouth when you speak
2.
the part of a musical instrument that you place between your lips
—picture at piccolo
3.
mouthpiece (of / for sb) a person, newspaper, etc. that speaks on behalf of another person or group of people :
The newspaper has become the official mouthpiece of the opposition party.
The Press Secretary serves as the President's mouthpiece.