A distortion of the countenance, whether habitual, from affectation, or momentary and occasional, to express some feeling, as contempt, disapprobation, complacency, etc.; a smirk; a made-up face.
source: Webster 1913
verb
contort the face to indicate a certain mental or emotional state
He grimaced when he saw the amount of homework he had to do.
source: WordNet 3.0
To make grimaces; to distort one's face; to make faces.
