Also found in: Thesaurus, Idioms, Wikipedia.
v. grinned, grin·ning, grins
To smile broadly, often baring the teeth, as in amusement, glee, embarrassment, or other strong emotion.
To express with a grin: I grinned my approval.
1. The act of grinning.
2. The facial expression produced by grinning.
[Middle English grennen, to grimace, from Old English grennian.]