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peroxide

American  
[puh-rok-sahyd] / pəˈrɒk saɪd /

noun

  • peroxides
    plural
  1. Chemistry.

    1. hydrogen peroxide, H 2 O 2 or H–O–O–H.

    2. a compound containing the bivalent group –O 2 –, derived from hydrogen peroxide, as sodium peroxide, Na 2 O 2 , or dimethyl peroxide, C 3 H 6 O 2 .

    3. the oxide of an element that contains an unusually large amount of oxygen.


verb (used with object)

  • peroxides,
    present (3rd person singular)
  • peroxided,
    past participle,  past
  • peroxiding
    present participle
  1. to use peroxide as a bleaching agent on (especially the hair).

peroxide British  
/ pəˈrɒksaɪd /

noun

  1. short for hydrogen peroxide, esp when used for bleaching hair

  2. any of a class of metallic oxides, such as sodium peroxide, Na 2 O 2 , that contain the divalent ion O-O

  3. (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

  4. any of a class of organic compounds whose molecules contain two oxygen atoms bound together. They tend to be explosive

  5. (modifier) of, relating to, bleached with, or resembling 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

verb

  1. (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
peroxide Scientific  
/ pə-rŏksīd′ /
  1. A compound containing the group O 2. 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.

  2. Hydrogen peroxide.


Other Word Forms

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Etymology

Origin of peroxide

First recorded in 1795–1805; per- + oxide

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

Together, these features help balance the different reaction speeds of oxygen reduction and water oxidation, two half-reactions that must work together during hydrogen peroxide production.

From Science Daily Aug. 6, 2026

Officials have been using chemicals, including reportedly hydrogen peroxide, to clean a green algae bloom which has taken hold in the pool since it was re-filled following a paint job earlier this month.

From BBC Jun. 22, 2026

National Park Service workers this week have been trying to clean the algae blooms off the bottom of the 2,000-foot-long pool by pouring hydrogen peroxide into the water and vacuuming the floor.

From The Wall Street Journal Jun. 21, 2026

As workers scrambled to pump out murky water and dumped hydrogen peroxide into the pool, Trump took no responsibility for what many observers chalked up to shoddy workmanship.

From Barron's Jun. 21, 2026

Lilya was an eccentric beauty, a petite blonde who regularly sent her aircraft mechanic to pick up peroxide from a nearby hospital so she could bleach her hair.

From "A Thousand Sisters" by Elizabeth Wein

This allows GPX4 to neutralize lipid peroxides, harmful molecules that would otherwise damage the membrane.

From Science Daily Dec. 9, 2025

Larger fines were assessed for failing to designate a point person to help fight the fire and failing to give a complete inventory of the organic peroxides on site when firefighters arrived, she said.

From Seattle Times Sep. 25, 2023

The ROSs and lipid peroxides then triggered intensive oxidative bursts, while the protons lowered the intracellular pH value, creating an unfavourable acidic microenvironment for the cancer cells.

From Science Daily Sep. 20, 2023

When ozone wafts into buildings, it reacts with limonene and similar molecules called monoterpenes, turning them into peroxides, alcohols, and other molecules that grow into airborne particles.

From Science Magazine Feb. 24, 2022

Oxidation without driers was effected probably through the formation of peroxides.

From Paint Technology and Tests by Henry A. Gardner

Puffy-faced and peroxided, Koepka finally admitted, “I’ll be honest: I can’t compete with these guys week in and week out.”

From Washington Post Feb. 22, 2023

Murray SawChuck, 38, a magician known for his spiky peroxided hair and a self-anointed role as “the Dennis the Menace of magic,” notes he is free in the evenings to attend other shows.

From The Wall Street Journal Oct. 5, 2016

With his peroxided locks, heavy mascara and volatile sensitivity, his Jackson is a cross between punky rockers Billy Idol and Billie Joe Armstrong, with a dash of corrupt, rabble-rousing politico Huey Long thrown in.

From Seattle Times Sep. 21, 2012

When we meet to photograph him, he still has the fluffy blond hair from the role – peroxided because there was no budget for wigs.

From The Guardian Jul. 22, 2010

When it was Dad’s move, I’d steal looks at him in his button-down shirt, trying to remember the fast-fading picture of the guy with peroxided hair and a leather jacket.

From "If I Stay" by Gayle Forman

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