cornea n.

Proto-Indo-European root meaning "horn; head," with derivatives referring to horned animals, horn-shaped objects, and projecting parts.

It forms all or part of: alpenhorn; Capricorn; carat; carotid; carrot; carotene; cerato-; cerebellum; cerebral; cerebrum; cervical; cervix; charivari; cheer; chelicerae; corn (n.2) "hardening of the skin;" cornea; corner; cornet; cornucopia; cranium; flugelhorn; hart; hartebeest; horn; hornbeam; hornblende; hornet; keratin; kerato-; migraine; monoceros; reindeer; rhinoceros; saveloy; serval; triceratops; unicorn.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit srngam "horn;" Persian sar "head," Avestan sarah- "head;" Greek karnon "horn," koryne "club, mace," koryphe "head;" Latin cornu "horn," cervus "deer;" Old English horn "horn of an animal;" Welsh carw "deer."

before vowels, kerat-, scientific word-forming element meaning "horn, horny," also "cornea of the eye" (see cornea), from Greek keras (genitive keratos) "the horn of an animal; horn as a material," from PIE root *ker- (1) "horn; head."