1. Ingtrown eyelash; trichoma; trichomatosis: Trichiasis is the hair growing in toward an orifice or against the eyeball.

Trichiasis is a condition in which the hair adjacent to a natural orifice turns inward and causes irritation; e.g., an inversion of an eyelid (entropion), eyelashes irritate the eye.

Trichiasis is a disease of the eye, in which the eyelashes, being turned in upon the eyeball, produce constant irritation by the motion of the lids.

The acquired type usually follows an inflammatory condition that produces distortion of sight.
2. The presence of minute hairlike filaments in the urine: Trichiasis is a medical ailment of the kidneys or of the bladder in which filamentous material, like hairs, are emitted from the urine.

An incurvation of the hairs around the excretory opening at the end of the alimentary canal: Mr. Black had a case of trichiasis of the anus which consequently irritated the mucous membrane around the opening.