Source : Webster's Revised Unabridged Dictionary (1913)

Trichiasis \Tri*chi"a*sis\, n. [NL., fr. Gr. ?, fr. tri`x,
   tricho`s, hair.] (Med.)
   A disease of the eye, in which the eyelashes, being turned in
   upon the eyeball, produce constant irritation by the motion
   of the lids.