n. hairball: a mass of swallowed hair in the stomach or gastrointestinal tract. See bezoar.
The habit of constantly pulling out one’s hair. It can be associated with severe mental handicap or with a psychotic illness. It may also occur in psychologically disturbed children. The sufferer typically pulls, twists, and breaks off chunks of hair from the scalp, leaving bald patches; occasionally, pubic hair is pulled out. Children sometimes eat the removed hair, which may form a hairball in the stomach, known medically as a trichobezoar (see bezoar). Treatment depends on the cause, and may consist of psychotherapy or antipsychotic drugs.... trichotillomania
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