hydrogen peroxide

American  

noun

1. a colorless, unstable, oily liquid, H 2 O 2 , an aqueous solution of which is used chiefly as an antiseptic and a bleaching agent.

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hydrogen peroxide British  

noun

1. a colourless oily unstable liquid, usually used in aqueous solution. It is a strong oxidizing agent used as a bleach for textiles, wood pulp, hair, etc, and as an oxidizer in rocket fuels. Formula: H 2 O 2

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hydrogen peroxide Scientific  

1. A colorless, dense liquid, that is often used as a bleach or is diluted with water for use as an antiseptic. Chemical formula: H ₂ O ₂ .

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Etymology

Origin of hydrogen peroxide

First recorded in 1870–75

Example Sentences

See Examples For:

hydrogen peroxide

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

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

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

Until well into the second half of the century, the formula H2O2 might mean water to one chemist but hydrogen peroxide to another.

From "A Short History of Nearly Everything" by Bill Bryson