Definitions for niacinˈnaɪ ə sɪn
Random House Webster's College Dictionary
ni•a•cinˈnaɪ ə sɪn(n.)
Ref: nicotinic acid.
Origin of niacin:
niacin, nicotinic acid(noun)
a B vitamin essential for the normal function of the nervous system and the gastrointestinal tract
A water-soluble vitamin, a component of vitamin B complex, found in meat, yeast, and dairy products; it is essential to metabolism.
U.S. National Library of Medicine
A water-soluble vitamin of the B complex occurring in various animal and plant tissues. It is required by the body for the formation of coenzymes NAD and NADP. It has PELLAGRA-curative, vasodilating, and antilipemic properties.