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[uhn-did] /ʌnˈdɪd/
simple past tense of undo.


[uhn-doo] /ʌnˈdu/
verb (used with object), undid, undone, undoing.
to reverse the doing of; cause to be as if never done:
Murder once done can never be undone.
to do away with; erase; efface:
to undo the havoc done by the storm.
to bring to ruin or disaster; destroy:
In the end his lies undid him.
to unfasten by releasing:
to undo a gate; to undo a button.
to untie or loose (a knot, rope, etc.).
to open (a package, wrapping, etc.).
Archaic. to explain; interpret.
Origin of undo
before 900; Middle English; Old English undōn; cognate with Dutch ontdoen. See un-2, do1
Related forms
undoable, adjective
Can be confused
undo, undue. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for undid
Contemporary Examples
Historical Examples
  • Neville undid his railway rug and wrapped it round her, for the rain had made the air very chilly.

    The Old Pincushion Mrs. Molesworth
  • The Prince stood by the window and undid the packet with trembling hands.

  • Then he undid the clumsy knot with which the watchman had pinioned her hands.

    The Tangled Skein Emmuska Orczy, Baroness Orczy
  • She took down the parcel from the shelf and undid the string.

    One Day's Courtship Robert Barr
  • In desperate haste he undid the door, and rushing in, closed and barred it fast, to shut out the spell of the conquering Sword.

    The Shadow Witch Gertrude Crownfield
  • Juve relighted the lamp, and undid the black serge covering of the bundle.

    A Nest of Spies Pierre Souvestre
  • But whether the action was right or wrong, and I am afraid it was not altogether right, I undid the packet.

    Lavengro George Borrow
  • He undid the wrapping of the lawyer's letter and, as he read, the blood went from his face.

    Murder Point Coningsby Dawson
  • A bystander came forward and undid the door, and a tall woman stood on the step of the coach looking around her.

    A German Pompadour Marie Hay
British Dictionary definitions for undid


the past tense of undo


verb (mainly transitive) -does, -doing, -did, -done
(also intransitive) to untie, unwrap, or open or become untied, unwrapped, etc
to reverse the effects of
to cause the downfall of
(obsolete) to explain or solve
Derived Forms
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
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Word Origin and History for undid



Old English undon "to unfasten and open" (a window or door), "to unfasten by releasing from a fixed position," from un- (2) + do (v.). The notion is of "to annul something that was done." Related: Undone; undoing.

Online Etymology Dictionary, © 2010 Douglas Harper
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