undo

[ uhn-doo ]
See synonyms for undo on Thesaurus.com
verb (used with object),un·did [uhn-did], /ʌnˈdɪd/, un·done [uhn-duhn], /ʌnˈdʌn/, un·do·ing.
  1. to reverse the doing of; cause to be as if never done: Murder once done can never be undone.

  2. to do away with; erase; efface: to undo the havoc done by the storm.

  1. to bring to ruin or disaster; destroy: In the end his lies undid him.

  2. to unfasten by releasing: to undo a gate; to undo a button.

  3. to untie or loose (a knot, rope, etc.).

  4. to open (a package, wrapping, etc.).

  5. Archaic. to explain; interpret.

Origin of undo

1
First recorded before 900; Middle English; Old English undōn; cognate with Dutch ontdoen; see origin at un-2, do1

Other words from undo

  • un·do·a·ble, adjective

Words that may be confused with undo

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use undo in a sentence

  • It undoes some of the progress made after 9/11 to push information out of agency silos and share it widely across the government.

    WikiLeaks’ Harmful New Dump | P.J. Crowley | August 31, 2011 | THE DAILY BEAST
  • Then Yvette, who is married to an older intellectual, undoes her skirt and waits for Salim in his bed.

    Naipaul's Art of Darkness | Amitava Kumar | December 26, 2008 | THE DAILY BEAST
  • Every gain on the wrong side undoes the effect of many conquests on the right.

    Your Mind and How to Use It | William Walker Atkinson
  • It undoes in a moment all that we have accomplished in a long while.

    Health Through Will Power | James J. Walsh
  • Then he goes to the tent, undoes a hook, and again stands gazing over the sea; then turns round, and resumes his walk as before.

    Fridtjof Nansen | Jacob B. Bull

British Dictionary definitions for undo

undo

/ (ʌnˈduː) /


verb-does, -doing, -did or -done (mainly tr)
  1. (also intr) to untie, unwrap, or open or become untied, unwrapped, etc

  2. to reverse the effects of

  1. to cause the downfall of

  2. obsolete to explain or solve

Derived forms of undo

  • undoer, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012