noun

1. any of a number of unrelated, complex organic substances found variously in most foods, or sometimes synthesized in the body, and essential, in small amounts, for the regulation of the metabolism and normal growth and functioning of the body
2. a dose of such a substance or of a group of such substances, taken, as in a tablet, as a dietary supplement

Etymology: earlier vitamine < Ger: so named (1913) by C. Funk (1884-1967), Pol biochemist < L vita, life (see vital) + Ger amin, amine: from the orig. mistaken idea that these substances all contain amino acids