Source : Webster's Revised Unabridged Dictionary (1913)

Glaucoma \Glau*co"ma\, n. [L., fr. Gr. ?, fr. ? light gray, blue
   gray.] (Med.)
   Dimness or abolition of sight, with a diminution of
   transparency, a bluish or greenish tinge of the refracting
   media of the eye, and a hard inelastic condition of the
   eyeball, with marked increase of tension within the eyeball.

Source : WordNet®

glaucoma
     n : increased pressure in the eyeball due to obstruction of the
         outflow of aqueous humor; damages the optic disc and
         impairs vision (sometimes progressing to blindness)