1. Therapeutic agent; any substance, other than food, used in the prevention, diagnosis, alleviation, treatment, or cure of disease. For types or classifications of drugs, see the specific name.
2. To administer or take a drug, usually implying an overly large quantity or a narcotic.
3. General term for any substance, stimulating or depressing, that can be habituating or addictive, especially a narcotic.
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