tr.v. un·der·lay (-lā), un·der·lain (-lān), un·der·ly·ing, un·der·lies
1. To be located under or below.
2. To be the support or basis of; account for: Many factors underlie my decision.
3. To constitute a prior claim over.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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.