- [noun] a part that goes over or into the mouth of a person; "the mouthpiece of a respirator"
- [noun] an acoustic device; the part of a telephone into which a person speaks
- [noun] a spokesperson (as a lawyer)
- [noun] (especially boxing) equipment that protects an athlete's mouth
- [noun] the tube of a pipe or cigarette holder that a smoker holds in the mouth
- [noun] the aperture of a wind instrument into which the player blows directly