gape

Short definition from Wiktionary

Verb

1. 1
   To open the mouth wide, especially involuntarily, as in a yawn, anger, or surprise.
2. 2
   To stare in wonder.
3. 3
   To open wide; to display a gap.
4. 4
   To open the passage to the vomeronasal organ, analogous to the flehming in other animals.
5. 5
   To depict a dilated anal or vaginal cavity upon penetrative sexual activity.

Noun

1. 1
   An act of gaping; a yawn.
2. 2
   A large opening.
3. 3
   A disease in poultry caused by gapeworm in the windpipe, a symptom of which is frequent gaping.
4. 4
   The width of an opening.
5. 5
   The maximum opening of the mouth (of a bird, fish, etc.) when it is open.