Part of Speech: Noun
1. Definition: a vitamin essential for normal vision (C20H30O); it prevents night blindness or inflammation or dryness of the eyes; same as vitamin A. One U.S.P. unit of vitamin A is equivalent to 0.30 micrograms of pure vitamin A alcohol.
Synonym: -- vitamin A; vitamin A alcohol; antiophthalmic factor; biosterol; retinol; A.