Wordnet 3.0
NOUN (1)
1. 
 a viscous alcohol that is less active in mammals than is vitamin A1; 
[syn: vitamin A2, dehydroretinol]
The Collaborative International Dictionary of English v.0.48:
vitamin A2 \vitamin A2\ n.
   dehydroretinol (C20H28O), one of the substances also called
   vitamin A. It has about 40% of the bioactivity of vitamin
   A1.
   Syn: dehydroretinol.
        [WordNet 1.5 +PJC]
WordNet (r) 3.0 (2006):
vitamin A2
    n 1: a viscous alcohol that is less active in mammals than is
         vitamin A1 [syn: vitamin A2, dehydroretinol]