Definition of "acidify" [a•cid•i•fy]

• To make or become acid. (verb-transitive)

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.

• "Because excess CO2 dissolves in the ocean - causing it to 'acidify' - researchers have been concerned about the ability of certain organisms to maintain the strength of their shells."
• "Adding large amounts of organic matter, such as peat moss and composted leaves, will acidify the soil as it breaks down."
• "Case in point the belief (raised in this very thread) that rising CO2 will NOT cause the atmosphere to retain more heat and acidify the oceans."