nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The weight of a substance that will combine with or replace one mole of hydrogen or one-half mole of oxygen. The equivalent weight is equal to the atomic weight divided by the valence.