A drug is a chemical which is given to people in order to treat or prevent an illness or disease.

Drugs are substances that some people take because of their pleasant effects, but which are usually illegal.

If you drug a person or animal, you give them a chemical substance in order to make them sleepy or unconscious.

If food or drink is drugged, a chemical substance is added to it in order to make someone sleepy or unconscious when they eat or drink it.