|Also called: tannic acid any of a class of yellowish or brownish solid compounds found in many plants and used as tanning agents, mordants, medical astringents, etc. Tannins are derivatives of gallic acid with the approximate formula C76H52O46|
|[C19: from French tanin, from |
|a colorless, oily, water-soluble, highly toxic, liquid alkaloid, C10H14N2, found in tobacco and valued as an insecticide|
|a compound capable of changing state or becoming inactive when subjected to heat or radiation|
|tannin (tān'ĭn) Pronunciation Key
Any of various compounds, including tannic acid, that occur naturally in the bark and fruit of various plants, especially the nutgalls, certain oaks, and sumac. Tannins are polyphenols, and form yellowish to light brown amorphous masses that can be powdery, flaky, or spongy. They are used in photography, dyeing, in tanning leather, in clarifying wine and beer, and as an astringent in medicine. Tannins are also an important ingredient in tea.