the part of something that is designed to be in or near the user's mouth, such as the part of a musical instrument that is blown into or the part of a phone that is spoken into;
e.g. The mouthpiece of his saxophone is specially designed to be more comfortable to use. She covered the phone's mouthpiece before asking us when we were leaving.
(noun)
(often derogatory) a person or organization that communicates the views of another person/organization and speaks on their behalf;
e.g. They needed a spokesperson to represent them well for the media.