tr.v. warned, warn·ing, warns
1. To notify or make aware in advance of something, especially of possible danger or misfortune: warned boaters of the coming storm; warned me that they might be delayed.
2. To make known (a warning): warned that the bolts needed to be replaced.
3. To advise or caution (someone) about a course of action: warned us to be careful; warned us not to stay up too late.
4. To notify (a person) to go or stay away: The ranger warned hikers away from the cliff.
[Middle English warnen, from Old English warnian; see wer-4 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.