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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.


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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:

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

In an effort combat the algae in the Reflecting Pool, employees of the National Park Service were seen pouring in gallons of hydrogen peroxide, a chemical commonly used in pool maintenance.

From Los Angeles Times Jun. 20, 2026

In response, crews reportedly used hydrogen peroxide treatments to address water quality issues, restoring just the outer rim of the pool to its blue coloration while leaving other areas still very green in appearance.

From Salon Jun. 19, 2026

The right dose of hydrogen peroxide would be “very, very high and they would have to stir it throughout the entire reflecting pool,” Bidelspach said.

From The Wall Street Journal Jun. 18, 2026

Hazel had a flash of a memory—Jack’s mom standing in front of her on some long-ago summer day, gently putting peroxide on a badly skinned knee, wincing along with Hazel.

From "Breadcrumbs" by Anne Ursu

The altered enzyme can no longer insert itself into the membrane correctly, leaving lipid peroxides free to accumulate.

From Science Daily Dec. 9, 2025

Taiwanese law requires organic peroxides to be stored in a separate warehouse building, but Launch Technologies kept the material on the first floor of the factory building, Chou said.

From Seattle Times Sep. 25, 2023

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

Lead and manganese are partially separated as peroxides, but the remaining metals are not deposited from acid solutions.

From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" by Various

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

An earlier version of this review misidentified the film still of peroxided children shown in “R.R.R.E.D.”

From New York Times Aug. 20, 2018

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 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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