antioxidant

noun

an·​ti·​ox·​i·​dant ˌan-tē-ˈäk-sə-dənt 

ˌan-ˌtī-

: a substance (such as beta-carotene or vitamin C) that inhibits oxidation or reactions promoted by oxygen, peroxides, or free radicals

antioxidant adjective

Examples of antioxidant in a Sentence

Recent Examples on the Web

These vegetables are rich in fiber, vitamins, antioxidants and glucosinolates, Goy said. —Andrea Margolis, FOXNews.com, 11 Mar. 2026

An antioxidant, the ingredient also fends off free radicals to slow hyperpigmentation, among other signs of aging. —Sophie Wirt, InStyle, 11 Mar. 2026

Full of fiber and antioxidants, sorghum packs in an impressive amount of protein (about 10 grams per cup) for a whole grain. —Katlyn Moncada, Better Homes & Gardens, 11 Mar. 2026

Importantly, antioxidants from fruits and vegetables (the color) are missing from boy kibble. —Melissa Willets, Parents, 10 Mar. 2026

Word History

First Known Use

1919, in the meaning defined above

Rhymes for antioxidant

• oxidant

Kids Definition

antioxidant

noun

an·​ti·​ox·​i·​dant ˌant-ē-ˈäk-səd-ənt 

ˌan-ˌtī-

: a substance that opposes oxidation or prevents or makes difficult reactions made easier by oxygen

Medical Definition

antioxidant

noun

an·​ti·​ox·​i·​dant ˌant-ē-ˈäk-səd-ənt, ˌan-ˌtī- 

: any of various substances (as beta-carotene, vitamin C, and alpha-tocopherol) that inhibit oxidation or reactions promoted by oxygen and peroxides and that include many held to protect the living body from the deleterious effects of free radicals

antioxidant adjective