The Collaborative International Dictionary of English v.0.48:

axerophthol \axerophthol\ n.
   1. 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.

   Syn: vitamin A; vitamin A alcohol; antiophthalmic factor;
        biosterol; retinol; A.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

axerophthol
    n 1: any of several fat-soluble vitamins essential for normal
         vision; prevents night blindness or inflammation or dryness
         of the eyes [syn: vitamin A, antiophthalmic factor,
         axerophthol, A]