smirk

From Middle English smirken, from Old English smearcian (“to smile”), corresponding to smerian + -cian (English -k; compare talk and stalk from, respectively, tell and steal). The former element from Proto-Germanic *smarōną (“to mock, scoff at”), and the latter from Proto-Germanic *-kōną. Compare Middle High German smielen/smieren (“to smile”) ( > obsolete, rare German schmieren). Doublet of smile.

The specific meaning of a mocking or unpleasant, malicious smile or grin develops in Early Modern English, but until the 18th century, it could still be used to describe a generic smile.