Definition of "tannic acid" []

• A white or yellowish astringent powder, C14H10O9, derived from nutgalls and used as a denaturant and in tanning and textiles. (noun)
• A lustrous yellowish to light brown amorphous, powdered, flaked, or spongy mass having the approximate composition C76H52O46, derived from the bark and fruit of many plants and used in photography, as a mordant, and to clarify wine and beer. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.