'coenzyme' definitions:

Definition of 'coenzyme'

From: WordNet
noun
A small molecule (not a protein but sometimes a vitamin) essential for the activity of some enzymes

Definition of 'coenzyme'

From: GCIDE
  • coenzyme \co*en"zyme\ (k[-o]*[e^]n"z[imac]m), (Biochem.) a molecule that is essential for the activity of some enzymes; it may exist free in solution within a living organism, but functions by binding to an enzyme to assist in catalyzing a reaction. The molecule itself may be temporarily changed during the reaction, but is ultimately restored to its original form. Many vitamins function as coenzymes. [PJC]