Smile
Middle English: perhaps of Scandinavian origin; related to smirk.
wiktionary
From Middle English smilen(“to smile”), from Old Norse smíla(“to smile”) (compare Danish smile, Swedish smila(“to smile”)), from Proto-Germanic *smīlijaną, *smirōną(“to smile”), from Proto-Indo-European *smey-(“to laugh, be glad, wonder”). Cognate with Saterland Frisian smielje(“to smile”), Low German smielen(“to smile”), Dutch smuilen(“to smile”), Middle High German smielen(“to smile”). Related also to Old High German smierōn(“to smile”), Old English smerian(“to laugh at”), Old English smercian, smearcian("to smile"; > English smirk), Latin miror(“to wonder at”).
etymonline
smile (v.)
c. 1300, perhaps from Middle Low German *smilen or a Scandinavian source (such as Danish smile "smile," Swedish smila "smile, smirk, simper, fawn"), from Proto-Germanic *smil-, extended form of PIE root *smei- "to laugh, smile" (source also of Sanskrit smayate "smiles;" Latvian smiêt "to laugh;" Latin mirus "wonderful," mirari "to wonder;" Old English smerian "to laugh at, scorn," Old High German smieron "to smile"). Related: Smiled; smiling.
It gradually pushed the usual Old English word, smearcian (modern smirk), into a specific, unpleasant sense. Of the eyes, from 1759. Figuratively, as indicating favor or encouragement, from c. 1400. Romance, Celtic, and Slavic languages tend to use a diminutive of the word for "laugh" to mean "smile" (such as Latin ridere "laugh;" subridere "smile"), perhaps literally "small laugh" or "low laugh."
smile (n.)
1560s, from smile (v.).
