Definition of "carbonic acid" [carbonic acid]

• A weak, unstable acid, H2CO3, present in solutions of carbon dioxide in water. (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.

• "Helmont, who was the first to prove the existence of carbonic acid and of fixed alkalies, wrote about Spa."
• "Till at last, I suppose, one does rise, like Eliphaz the Temanite; states that his inner man is bursting (as if filled with carbonic acid and new wine), that by the favor of Heaven he will speak a word or two."