axerophthol(n = noun.substance) a, antiophthalmic factor, vitamin a - any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes;
is a kind of fat-soluble vitamin
has particulars: retinol, vitamin a1, dehydroretinol, vitamin a2

   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. [WordNet 1.5]