A powerful narcotic alkaloid, C17H21NO4, obtained from the leaves of coca. It is a bitter, white, crystalline substance, and is remarkable for producing local insensibility to pain. It is classified as addictive and is not available in the U. S. without a prescription, but is nevertheless one of the most widespread illegal drugs of abuse. It is used in several forms, including small pellets of free base, called crack. Most of the cacaine illegally used in the U.S. is imported.