—n. Chem. a. hydrogen peroxide, H2O2 or H–O–O–H.
b. a compound containing the bivalent group –O2–, derived from hydrogen peroxide, as sodium peroxide, Na2O2, or dimethyl peroxide, C3H6O2.
c. the oxide of an element that contains an unusually large amount of oxygen.
—v.t. to use peroxide as a bleaching agent on (esp. the hair).