# peroxide

/pɝˈɑkˌsaɪd/ (US) · /pəɹˈɒksaɪd/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/peroxide
Updated: 2026-05-08

## Definition

a strong chemical liquid used to kill germs or to make hair much lighter in color. You might use it on a small cut or to bleach your hair blonde.

For teachers: a chemical compound containing two oxygen atoms bonded together, most commonly referring to hydrogen peroxide. Often used as an antiseptic, a bleaching agent, or an oxidising agent in industrial processes.

## Examples

- She used peroxide to make her hair blonde.
- The nurse cleaned the minor wound with a diluted solution of peroxide to prevent infection.
- In industrial chemistry, peroxides serve as powerful oxidising agents, though they require careful handling due to their inherent instability and potential for explosive decomposition under certain thermal conditions.

## Usage notes

- Uncountable when referring to the chemical substance in general; countable when referring to specific chemical variations or types.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.