cornea

from WordNet (r) 3.0 (2006)

cornea
    n 1: the transparent dome-shaped anterior portion of the outer
         covering of the eye; it covers the iris and pupil and is
         continuous with the sclera

from The Collaborative International Dictionary of English v.0.48

Cornea \Cor"ne*a\ (k?r"n?-?), n.; pl. {Corneas} (-?z). [Fem.
   sing., fr. L. corneus horny, fr. cornu a horn. See {Horn}.]
   (Anat.)
   The transparent part of the coat of the eyeball which covers
   the iris and pupil and admits light to the interior. See
   {Eye}.
   [1913 Webster]