DRUG (from Fr. drogue, a word common in Romance languages, cf. Span. and Ital. droga; the origin of the word is obscure, but may possibly be connected with Dutch droog, dry), any organic and inorganic substance used in the preparation of medicines, by itself or in combination with others, and either prepared by some method or used in a natural state (see Pharmacology and Pharmacopoeia). In a particular sense "drug" is often used synonymously for narcotics or poisonous substances, and hence "to drug" means to stupefy or poison. The word is also applied to any article for which there is no sale, or of which the value has greatly depreciated - a "drug in the market."
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)