The American Heritage® Dictionary of the English Language, 4th Edition
n. A white crystalline acid, C5H4NCOOH, that is a component of the vitamin B complex found in meat, wheat germ, dairy products, and yeast and is used to treat and prevent pellagra. Also called nicotinic acid.
n. A water-soluble vitamin, a component of vitamin B complex, found in meat, yeast, and dairy products; it is essential to metabolism.
the GNU version of the Collaborative International Dictionary of English
n. A B vitamin (vitamin B5) essential for the normal function of the nervous system and the gastrointestinal tract. Called also nicotinic acid and antipellagra vitamin. Chemical formula C6H5NO2, chemically it is 3-pyridinecarboxylic acid.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a B vitamin essential for the normal function of the nervous system and the gastrointestinal tract
Word Usage
"However, by some sort of luck, this process also makes the vitamin niacin available from the grain, thus preventing pellagra (niacin deficency), a rather debilitating disease."