Definition of drug

 The word "drug" means anything that, even

 in small amounts, produces changes in the

body, the mind, or both. This definition,

however, does not clearly separate drugs

from what we usually think of as food. The

difference between a drug and a poison is

also unclear. All drugs become poisons in

large amounts, and many poisons are useful

drugs in carefully controlled amounts. Is

alcohol, for instance, a food, a drug, or

a poison? It can be any of the three,

depending on how we use it.