Definition of "acid" []

• Chemistry Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts. (noun)
• Chemistry A substance that yields hydrogen ions when dissolved in water. (noun)
• Chemistry A substance that can act as a proton donor. (noun)
• Chemistry A substance that can accept a pair of electrons to form a covalent bond. (noun)
• A substance having a sour taste. (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.

• "‡ Figuratively, acid applies to anything sour or biting; for example, an “acid wit” is sharp and unpleasant."
• "The commercial acid, often called _muriatic acid_, is usually colored yellow by impurities."
• "An excess of the trioxide may dissolve in the strong sulphuric acid, forming what is known as _fuming sulphuric acid_."