crack cocaine

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Chemically purified, very potent cocaine in pellet form that is smoked through a glass pipe and is considered highly and rapidly addictive.

Wiktionary

1. n. A mixture of baking soda and cocaine in solid form that is smoked in a pipe as a narcotic.
2. n. A mixture of salt substitute, ether, and cocaine in a semi-liquid form is far more potent than if made with baking soda alone.

WordNet 3.0

1. n. a purified and potent form of cocaine that is smoked rather than snorted; highly addictive