1920, originally vitamine (1912) coined by Polish biochemist Casimir Funk (1884-1967), from Latin vita "life" (see vital) + amine, because they were thought to contain amino acids. The terminal -e formally was stripped off when scientists learned the true nature of the substance; -in was acceptable because it was used for neutral substances of undefined composition. The lettering system of nomenclature (Vitamin A, B, C, etc.) was introduced at the same time (1920).
vitamin vi·ta·min (vī'tə-mĭn)
n.
Any of various fat-soluble or water-soluble organic substances essential in minute amounts for normal growth and activity of the body and obtained naturally from plant and animal foods.
Complex organic compounds that are needed in small amounts by the body for normal growth and metabolism. An important part of a balanced diet, vitamins occur naturally in foods and may be added to processed foods to increase their nutritional value. Many vitamins have been identified, and each plays a specific role in the functioning of the body. For example, vitamin C is needed for the proper healing of wounds and broken bones; vitamin A helps the body resist infection. Some vitamins are so important that without them certain diseases or conditions could develop. For example, a deficiency of vitamin D may cause rickets, and a deficiency of vitamin B8 could result in a form of anemia.