Webster's Revised Unabridged Dictionary · 1913

Chin

Chin (chin) , noun

[Anglo-Saxon cin, akin to Old Saxon kin, G kinn, Icelandic kinn, cheek, Danish & Swedish kind, Latin gena, Greek {not transcribed}; compare Sanskrit hanu. r232.]

1.
The lower extremity of the face below the mouth; the point of the under jaw.
2.
(Zoology) The exterior or under surface embraced between the branches of the lower jaw bone, in birds.