The Collaborative International Dictionary of English v.0.48:

coenzyme A \co*en"zyme A`\ (k[-o]*[e^]n"z[imac]m [=a]`),
   (Biochem.)
   a coenzyme (C21H36N7O16P3S) that participates in the
   transfer of acetyl groups in biochemical reactions; --
   abbreviated CoA. It contains adenosine, phosphate,
   pantothenic acid and cysteamine groups. The acetyl group to
   be transferred during biosynthesis is temporarily attached to
   the free sulhydryl of the cysteamine group to form a
   thioester, in which state it is called acetyl coenzyme A. The
   strength of a preparation of coenzyme A may be expressed by
   the Lippman unit; one milligram of CoA contains 413 Lippman
   units.
   [PJC]

WordNet (r) 3.0 (2006):

coenzyme A
    n 1: a coenzyme present in all living cells; essential to
         metabolism of carbohydrates and fats and some amino acids