A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage. "Drug." Dictionary.com Unabridged (v 1.1), Random House, Inc., via dictionary.com. Retrieved on . In pharmacology, a drug is "a chemical substance used in the treatment, cure, prevention, or diagnosis of disease or used… (More on Drug)