grimace (n.) Look up grimace at Dictionary.com
1650s, from French grimace, from Middle French grimache, from Old French grimuce "grotesque face, ugly mug," possibly from Frankish (compare Old Saxon grima "face mask," Old English grima "mask, helmet"), from same Germanic root as grim (adj.). With pejorative suffix -azo (from Latin -aceus).
grimace (v.) Look up grimace at Dictionary.com
1762, from French grimacer, from grimace (see grimace (n.)). Related: Grimaced; grimacing.