- a crystalline acid, C6H5NO2, that is a component of the vitamin-B complex, found in fresh meat, yeast, etc., produced by the oxidation of nicotine, and used in the prevention and treatment of pellagra.
- a vitamin of the B complex that occurs in milk, liver, yeast, etc. Lack of it in the diet leads to the disease pellagra. Formula: (C 5 H 4 N)COOHAlso called: niacin
- See niacin.