a colorless, syrupy liquid, HO, often used in dilute, unstable solutions as a bleaching or disinfecting agent, and in more concentrated form as a rocket fuel, in the production of foam rubber, etc.
See hydrogen peroxide in American Heritage Dictionary 4
noun
A colorless, heavy, strongly oxidizing liquid, H2O2, capable of reacting explosively with combustibles and used principally in aqueous solution as a mild antiseptic, a bleaching agent, an oxidizing agent, and a laboratory reagent.