tannin

American  

[tan-in] / ˈtæn ɪn /

noun

1. Chemistry. any of a group of astringent vegetable principles or compounds, chiefly complex glucosides of catechol and pyrogallol, as the reddish compound that gives the tanning properties to oak bark or the whitish compound that occurs in large quantities in nutgalls.

2. any of these compounds occurring in wine and imparting an astringent taste, especially in red wine.

---

tannin British  

/ ˈtænɪn /

noun

1. 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 C 76 H 52 O 46

---

tannin Scientific  

/ tăn′ĭn /

1. 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 bind proteins and are used in dyeing, in tanning leather, in clarifying wine and beer, and as an astringent in medicine. Tannins also give color and flavor to black tea.

2. Any of various other substances that promote the tanning of leather, such as chromium salts.

---

Other Word Forms

• nontannin
  noun

Etymology

Origin of tannin

First recorded in 1795–1805; earlier tanin, from French; see origin at tan ¹, -in ²

Example Sentences

Tannin is a type of phenolic compound – it's found in all plants and usually plays a role in preventing disease, resisting predation or encouraging seed dispersal by animals.

From Salon • Dec. 16, 2024

Tannin is also found in many fruits, vegetables and other plant materials.

From Washington Post • Apr. 7, 2023

The case of two Bear Stearns hedge fund managers — Ralph Cioffi and Matthew Tannin — was particularly instructive about how poorly federal prosecutors handled one of the very few cases they chose to pursue.

From New York Times • Aug. 16, 2017

Tannin is a compound that makes seed casings strong, so higher levels make those shells harder for seedlings to break through, delaying germination.

From Scientific American • May 16, 2015

Others use a dry dressing, and dust with Calomel, with a mixture of Sulphate of Copper, Sulphate of Zinc and Alum, or with Subacetate of Copper and Tannin.

From Diseases of the Horse's Foot by Reeks, Harry Caulton