chin (n.)

"lower extremity of the face below the mouth," Old English cin, cinn "chin," 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- (2), probably originally "jaw, jawbone," but also forming words for "chin, cheek."

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."

To take it on the chin "be hit hard," in a figurative sense, is from 1928, an image from pugilism. To keep (one's) chin up "remain optimistic amid adversity" is from 1938.

chin (v.)

1590s, "to press (affectionately) chin to chin," from chin (n.). Meaning "to bring to the chin" (of a fiddle) is from 1869. Slang meaning "to 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.