[ puh-rok-sahyd ]
/ pəˈrɒk saɪd /


  1. hydrogen peroxide, H2O2 or H–O–O–H.
  2. a compound containing the bivalent group –O2–, derived from hydrogen peroxide, as sodium peroxide, Na2O2, or dimethyl peroxide, C3H6O2.
  3. the oxide of an element that contains an unusually large amount of oxygen.

verb (used with object), per·ox·id·ed, per·ox·id·ing.

to use peroxide as a bleaching agent on (especially the hair).


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Origin of peroxide

First recorded in 1795–1805; per- + oxide


per·ox·id·ic [pur-ok-sid-ik] /ˌpɜr ɒkˈsɪd ɪk/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for peroxide

British Dictionary definitions for peroxide

/ (pəˈrɒksaɪd) /


short for hydrogen peroxide, esp when used for bleaching hair
any of a class of metallic oxides, such as sodium peroxide, Na 2 O 2, that contain the divalent ion O-O
(not in technical usage) any of certain dioxides, such as manganese peroxide, MnO 2, that resemble peroxides in their formula but do not contain the O-O ion
any of a class of organic compounds whose molecules contain two oxygen atoms bound together. They tend to be explosive
(modifier) of, relating to, bleached with, or resembling peroxide


(tr) to bleach (the hair) with peroxide
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for peroxide

[ pə-rŏksīd′ ]


A compound, such as sodium peroxide, that contains a peroxy group and yields hydrogen peroxide when treated with an acid.
Hydrogen peroxide.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for peroxide

[ pə-rŏksīd′ ]

A compound containing the group O2. Peroxides are strong oxidizers and are used as industrial bleaches. When any peroxide is combined with an acid, one of the products is hydrogen peroxide.
Hydrogen peroxide.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.