vitamin

UK: /ˈvɪtəmɪn/

US: /ˈvaɪtəmɪn/

US: (vī′tə min; Brit. also vit′ə min)

WordReference Random House Learner's Dictionary of American English © 2026

vi•ta•min /ˈvaɪtəmɪn/  also vi•ta•mine /ˈvaɪtəmɪn, -ˌmin/   n. [countable]

1. Biochemistry, Nutrition any of a group of substances that are essential to the body in small quantities for normal metabolism, found in very small amounts in foods and also produced artificially.

See -vit-.

WordReference Random House Unabridged Dictionary of American English © 2026

vi•ta•min  (vī′tə min; Brit. also vit′ə min), n. 

1. Biochemistry, Nutrition any of a group of organic substances essential in small quantities to normal metabolism, found in minute amounts in natural foodstuffs or sometimes produced synthetically: deficiencies of vitamins produce specific disorders.

Also, vi•ta•mine  (vī′tə min, -mēn′; Brit. also vit′ə min, -mēn′). 

• Latin vīt(a) life + amine; coined by C. Funk, who thought they were amines
• earlier vitamine 1912

vi′ta•min′ic, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

vitamin / ˈvɪtəmɪn ˈvaɪ-/ noun

1. any of a group of substances that are essential, in small quantities, for the normal functioning of metabolism in the body. They cannot usually be synthesized in the body but they occur naturally in certain foods: insufficient supply of any particular vitamin results in a deficiency disease

Etymology: 20th Century: vit- from Latin vīta life + -amin from amine; so named by Casimir Funk, who believed the substances to be amines

ˌvitaˈminic adjective