coun·ter·vail (koun′tər-vāl, kountər-vāl′)
v. coun·ter·vailed, coun·ter·vail·ing, coun·ter·vails
1. To act against with equal force; counteract.
2. To compensate for; offset.
To act against an often detrimental influence or power.
[Middle English countrevaillen, from Old French contrevaloir, contrevail- : contre-, counter- + valoir, to be worth (from Latin valēre, to be strong; see wal- in the Appendix of Indo-European roots).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.