mouthpiece
Concise Oxford English Dictionary © 2008 Oxford University Press:
mouthpiece/ˈmaʊθpiːs/
▶noun
- 1 a part of a musical instrument, telephone, etc., designed to be put in or against the mouth.
- 2 a gumshield.
- 3 chiefly derogatory a person who speaks on behalf of another person or an organization.
'mouthpiece' also found in these Oxford entries:

