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

Lutein and zeaxanthin have the ability to filter short-wavelength light and act as antioxidants. —Barbie Cervoni, Verywell Health, 7 Nov. 2025

Spinach is packed with the carotenoid antioxidants lutein and zeaxanthin, which support eye health. —Jillian Kubala, Health, 6 Nov. 2025

This conditioner can help restore strands to near virgin health with the help of arginine (a keratin building block that promotes growth) and astaxanthin (an antioxidant that defends against stress and damage). —Mary Honkus, Glamour, 29 Oct. 2025

Beyond cognitive benefits, lion’s mane also appears to have antioxidant and anti-inflammatory effects, which may help reduce oxidative stress – an underlying contributor to many chronic diseases. —Daryl Austin, USA Today, 29 Oct. 2025

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