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 (common tannin, tannic acid).
any of these compounds occurring in wine and imparting an astringent taste, especially in red wine.

Origin of tannin

1795–1805; earlier tanin < F. See tan1, -in2
Related formsnon·tan·nin, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for tannin

Contemporary Examples of tannin

  • Spanish oak, which has an open grain and high levels of tannin, gives you dried fruit, spice, and even chocolate flavors.

  • Sorry, tannin fans: “In contrast to results for coffee, no effect was observed for drinking tea,” the authors avow.

    The Daily Beast logo
    Can Coffee Save Your Life?

    Anneli Rufus

    October 28, 2011

  • And yet, late last week, Cioffi and Tannin were found not guilty of all charges.

    The Daily Beast logo
    Wall Street Will Walk

    Charlie Gasparino

    November 16, 2009

  • To be sure, the case against Cioffi and Tannin, such as it is, has some noteworthy elements.

    The Daily Beast logo
    Prosecutors Fumble Wall Street Probes

    Charlie Gasparino

    September 17, 2009

  • Cioffi and Tannin have both pleaded not guilty, so presumably they will also argue they did nothing wrong.

    The Daily Beast logo
    Who's Going Down?

    Charlie Gasparino

    May 13, 2009

Historical Examples of tannin

  • Animal skins also, in any form, uncombined with tannin, may be worked into glue.

  • It is sold in the form of crushed leaves or as a powder (15-20% tannin).

    Vegetable Dyes

    Ethel M. Mairet

  • There is no deception about it: it tastes of tannin and spruce and creosote.

    In the Wilderness

    Charles Dudley Warner

  • The tannin unites with the gelatine; and thus the hide becomes leather.

    Makers of Many Things

    Eva March Tappan

  • It is lots of work to get the tannin out of oak or hemlock bark.

    The Story of Leather

    Sara Ware Bassett

British Dictionary definitions for tannin



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 46Also called: tannic acid

Word Origin for tannin

C19: from French tanin, from tan 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for tannin

vegetable substance capable of converting animal hide to leather, 1802, from French tannin (1798), from tan "crushed oak bark containing tannin" (see tan (v.)). Tannic acid first recorded 1836, from French acide tannique, inroduced 1834 by Pelouze.

Online Etymology Dictionary, © 2010 Douglas Harper

tannin in Science



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.
Any of various other substances that promote the tanning of leather, such as chromium salts.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.