Definition of "tartaric acid" [tartaric acid]

• Any of four isomeric crystalline organic compounds, C4H6O6, used to make cream of tartar and baking powder, as a sequestrant, and in effervescent beverages and photographic chemicals. (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.

• "I now perceive the use my company is of to them both, better than I did when we set out: I furnish, as it were, the sugar and ginger, which makes the alkali of the one and the tartaric acid of the other effervesce into a somewhat more agreeable draught; for, "the effervescing of these people!""