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.

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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

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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.

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Other Word Forms

• nontannin noun

Etymology

Origin of tannin

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

Example Sentences

“We have to make our own from anything with tannin — oak galls, acorns or black walnuts — and let it sit to dye it black.”

From Los Angeles Times • Jan. 8, 2026

Over time, the balance of protein like, lignin like, and tannin like substances shifted depending on the type of plastic and the level of sunlight exposure.

From Science Daily • Dec. 31, 2025

According to Stonestreet winemaker Kristina Shideler, the fruit and tannin integration “start to unfold 3-4 years from bottling,” which means it’s drinking well right now.

From The Wall Street Journal • Nov. 27, 2025

Many components of red wine have been accused of causing this misery – sulfites, biogenic amines and tannin are the most popular.

From Salon • Dec. 16, 2024

In response, the neighboring oaks step up their tannin production the better to withstand the coming onslaught.

From "A Walk in the Woods" by Bill Bryson