The Collaborative International Dictionary of English v.0.48:

Retinol \Ret"i*nol\, n. [Gr. ??? resin + L. oleum oil.]
   1. (Chem.) A hydrocarbon oil C32H16, obtained by the
      distillation of resin, -- used as a solvent, as an
      antiseptic, and in printer's ink.
      [1913 Webster +PJC]

   2. One of the compounds which function as vitamin A. Called
      also vitamin A, vitamin A1 and vitamin A alcohol.
      See vitamin A1.
      [PJC]

WordNet (r) 3.0 (2006):

retinol
    n 1: an unsaturated alcohol that occurs in marine fish-liver
         oils and is synthesized biologically from carotene [syn:
         vitamin A1, retinol]