from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A drug used illegally and recreationally for its euphoric and other mind-altering effects such as: opiates, cannabinoids, benzodiazepines, amphetamines and others.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a drug that is taken for nonmedicinal reasons (usually for mind-altering effects); drug abuse can lead to physical and mental damage and (with some substances) dependence and addiction
This term comes from the fact that these types of substances are normally sold on the street by drug dealers. (Wiktionary)