Smile Definition & Meaning – Merriam-Webster

Etymology

Verb

Middle English smilen, going back to a Germanic verbal base *smil-, *smīl- (from earlier *smei̯l-) “smile,” probably an extension with -l- of Indo-European *smei̯- “laugh, smile,” whence Old Church Slavic smějǫ sę, smijati sę “to laugh,” Latvian smeju, smiêt “to laugh, mock,” Tocharian B smi- “smile,” Sanskrit smáyate “(s/he) smiles,” and with a -d- extension in Greek meidiáein “to smile,” philomeidḗs “with a friendly smile,” Latvian smaida “smile,” smaidît “to smile, mock”

Note:
The comparative set for this Germanic etymon do not show clear descent from a single form, perhaps due to its affective character. There is no attested Old English ancestor of Middle English smilen; a Scandinavian source has been suggested, but Danish smile “to smile” and Swedish smila, not attested before the 17th century, could be loans from an unattested Middle Low German verb. Old High German has smilenter (glossing Latin subridens “smiling”), with presumed long vowel, continued by Middle High German smielen. Kiliaen’s 1599 Dutch dictionary enters smuylen “subridere,” apparently with a different vocalism. Parallel to these are a group of forms with -r- rather than -l-: Old English smerian “to laugh, scorn,” Old High German smierēn, smierōn (with e2?) “to smile,” Old English bismerian and Old High German bismerōn “to mock, insult,” and, with different vocalism, Old English smǣr, smǣre “lip(s),” gālsmǣre “inclined to laugh, frivolous.” The forms with -r- have been compared with Sanskrit (Vedic) á-smera- “not bashful, confiding,” and particularly with Latin mīrus “remarkable, amazing,” presumed to be derivative of a neuter *mīrum, going back to a noun *smei̯-ro- “laughter, smiling,” (though a semantic shift from “laughter” to “astonishment” is questionable).

Noun

Middle English smyle, derivative of smilen “to smile entry 1”