vitamin

n. natural or manmade organic substances necessary for physical development and functioning

A vitamin is a nutrient that is an organic compound required in tiny amounts for essential metabolic reactions in a living organism. allowing supplementation of the dietary intake.
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Vitamin /vi·ta·min/ any of a group of unrelated organic substances occurring in many foods in small amounts and necessary in trace amounts for the [more]Vitamin - Community and Resources

Noun
1. any of a group of organic substances essential in small quantities to normal metabolism
(hypernym) nutriment, nourishment, nutrition, sustenance, aliment, alimentation, victuals
(hyponym) fat-soluble vitamin
(substance-holonym) multivitamin, multivitamin pill
(derivation) vitaminize, vitaminise

n. vitamin, natural or manmade organic substances necessary for physical development and functioning