What does "grimace" mean?

Grimace: A distortion of the countenance, whether habitual, from affectation, or momentary aad occasional, to express some feeling, as contempt, disapprobation, complacency, etc.; a smirk; a made-up face. Moving his face into such a hideons grimace, that every feature of it appeared under a different distortion. Addison. Note: "Half the French words used affectedly by Melantha in Dryden's "Marriage a-la-Mode," as innovations in our language, are now in common usa: chagrin, double--entendre, éclaircissement, embarras, équivoque, foible, grimace, naïvete, ridicule. All these words, which she learns by heart to use occasionally, are now in common use." I. Disraeli.