tartaric acidn. Any of three stereoisomeric crystalline organic dicarboxylic acids, C4H6O6, used to make cream of tartar and baking powder, as a sequestrant, and in effervescent beverages and photographic chemicals.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.tartaric acid n (Elements & Compounds) a colourless or white odourless crystalline water-soluble dicarboxylic acid existing in four stereoisomeric forms, the commonest being the dextrorotatory (d-) compound which is found in many fruits: used as a food additive (E334) in soft drinks, confectionery, and baking powders and in tanning and photography. Formula: HOOCCH(OH)CH(OH)COOH. Systematic name: 2,3-dihydroxybutanedioic acid Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014tar?tar?ic ac?id (t?r?tær ?k, -?t?r-) n. an organic compound, C4H6O6, occurring in four isomeric forms: used in effervescent beverages, baking powder, photography, and tanning. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.