adenosine triphosphate

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

• noun ATP.

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

• noun biochemistry A nucleotide that occurs in muscle tissue, and is used as a source of energy in cellular reactions, and in the synthesis of nucleic acids.
• noun biochemistry A neurotransmitter recognised by purinergic receptors.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a nucleotide derived from adenosine that occurs in muscle tissue; the major source of energy for cellular reactions