Grimace
WordNet
noun
(1) A contorted facial expression
"She made a grimace at the prospect"
verb
(2) Contort the face to indicate a certain mental or emotional state
"He grimaced when he saw the amount of homework he had to do"
WiktionaryText
Noun
- 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.
- "I trundle off to bed, eyes brimming, face twisted into a grateful glistening grimace, and awaken the next day wondering what all the fuss was about." — Opera News, March 2005