benzoyl peroxide

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A flammable white granular solid, C₁₄H₁₀O₄, used as a bleaching agent for flour and lipids, as a drying agent, as a polymerization catalyst, and in pharmaceuticals.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry A peroxide derived from benzoic acid; it is used to bleach flour, and in many industrial applications

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a white crystalline peroxide used in bleaching (flour or oils or fats) and as a catalyst for free radical reactions