—v.i. 1. to smile broadly, esp. as an indication of pleasure, amusement, or the like.
2. to draw back the lips so as to show the teeth, as a snarling dog or a person in pain.
3. to show or be exposed through an opening, crevice, etc.
—v.t. to express or produce by grinning: The little boy grinned his approval of the gift.
—n. 1. a broad smile.
2. the act of producing a broad smile.
3. the act of withdrawing the lips and showing the teeth, as in anger or pain.