chin (n.) Look up chin at
Old English cin, cinn "chin" (but in some compounds suggesting an older, broader sense of "jawbone"); a general Germanic word (compare Old Saxon and Old High German kinni; Old Norse kinn; German Kinn "chin;" Gothic kinnus "cheek"), from PIE root *genu-, probably originally "jaw, jawbone," but also forming words for "chin, cheek" (source also of Sanskrit hanuh "jaw," Avestan zanu- "chin;" Armenian cnawt "jawbone, cheek;" Lithuanian žándas "jawbone;" Greek genus "chin, lower jaw," geneion "chin;" Old Irish gin "mouth," Welsh gen "jawbone, chin").

The West Germanic words generally mean "chin," but there are traces of earlier use as "jaw," such as Old English cinbane "jawbone," and the words for "cheek," "chin," and "jaw" naturally overlap and interchange; compare cheek (n.), which originally meant "jaw," and Latin maxilla, which gave Italian mascella "jaw," but Spanish mejilla "cheek."
chin (v.) Look up chin at
1590s, "to press (affectionately) chin to chin," from chin (n.). Meaning "to bring to the chin" (of a fiddle) is from 1869. Slang meaning "talk, gossip" is from 1883, American English. Related: Chinned; chinning. Athletic sense of "raise one's chin over" (a raised bar, for exercise) is from 1880s.