chemical
any substance used in or resulting from a reaction involving changes to atoms or molecules, especially one derived artificially for practical use
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
chemical
[′kem·i·kəl] (chemistry)
Related to the science of chemistry.
A substance characterized by definite molecular composition.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.