flavonoid

noun

fla·​vo·​noid ˈflā-və-ˌnȯid 

: any of a large group of typically biologically active water-soluble plant compounds (such as the anthocyanins and flavones) that include pigments ranging in color from yellow to red to blue and occur especially in fruits, vegetables, and herbs (such as grapes, citrus fruits, peppers, and dill)

Blueberries are packed with a flavonoid known as anthocyanin, an antioxidant proven to help boost the immune system …

—Margaret Darby

Flavonoids are effective scavengers of free radicals in the test tube (in vitro). However, even with very high flavonoid intakes, plasma and intracellular flavonoid concentrations in humans are likely to be 100 to 1000 times lower than concentrations of other antioxidants …

—Jane Higdon

The rich palette of dyes in butterflies' wings are all derived from chemicals called flavonoids, which the insects cannot make themselves and must sequester from their food plants.

—Nicholas Wade

see bioflavonoid

Examples of flavonoid in a Sentence

Recent Examples on the Web

Their face mask is a multi-hyphenate formula that decongests pores, fades dark spots, and soothes skin with a blend of charcoal, organic flame tree, flavonoids, vitamin C, and aloe. —Kiana Murden, Vogue, 12 Dec. 2025

Including foods rich in omega-3s, antioxidants, and flavonoids is a simple way to add more of these brain-healthy nutrients to your plate. —Lindsey Desoto, Health, 11 Dec. 2025

Orange juice contains flavonoids and nutrients, such as vitamin C and potassium, that are beneficial for the heart. —Mira Miller, Verywell Health, 11 Dec. 2025

The findings highlight how citrus flavonoids — plant compounds also found in berries, tea and cocoa that act as antioxidants and anti-inflammatories — may influence the body at a molecular level. —Deirdre Bardolf, FOXNews.com, 18 Nov. 2025

Word History

Etymology

flavone + -oid

First Known Use

1947, in the meaning defined above

Medical Definition

flavonoid

1 of 2 adjective

fla·​vo·​noid ˈflāv-ə-ˌnȯid  ˈflav- 

: of, relating to, or being a flavonoid

flavonoid

2 of 2 noun

: any of a large group of typically biologically active, water-soluble, plant compounds (such as the flavones) that include pigments ranging in color from yellow to red to blue and occur especially in fruits, vegetables, and herbs (such as grapes, citrus fruits, peppers, and dill)

Tea contains substances called catechins (tea flavonoids) that may protect against heart disease and even cancer.

—UC Berkeley Wellness Newsletter

Flavonoids are effective scavengers of free radicals in the test tube (in vitro). However, even with very high flavonoid intakes, plasma and intracellular flavonoid concentrations in humans are likely to be 100 to 1000 times lower than concentrations of other antioxidants …

—Jane Higdon, An Evidence-Based Approach to Dietary Phytochemicals

Note: Flavonoids are polyphenolic 15-carbon compounds with a basic structure consisting of two benzene rings joined by a chain of 3 carbons.

see bioflavonoid