Definition: [noun] the opening and cavity in the lower part of the human face, surrounded by the lips, through which food is taken in and vocal sounds are emitted.
Example: Ben stood transfixed with disbelief, his mouth open
Definition: [noun] an opening or entrance to a hollow, concave, or enclosed structure.
Example: the mouth of a cave
Definition: [verb] move the lips as if saying (something).
Example: she mouthed a silent farewell
Definition: [verb] take in or touch with the mouth.
Example: puppies may mouth each other's collars during play