v. un·did (-dĭd), un·done (-dŭn), un·do·ing (-dĭng), un·does (-dŭz)
1. To reverse or erase; annul: impossible to undo the suffering caused by the war.
2. To untie, disassemble, or loosen: undo a shoelace.
3. To open (a parcel, for example); unwrap.
a. To cause the ruin or downfall of; destroy.
b. To throw into confusion; unsettle.
To come open or unfastened.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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.