coenzyme A

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A coenzyme present in all living cells that functions as an acyl group carrier and is necessary for fatty acid synthesis and oxidation, pyruvate oxidation, and other acetylation reactions.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biochemistry A coenzyme, formed from pantothenic acid and adenosine triphosphate, that is necessary for fatty acid synthesis and metabolism.