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undo

[uhn-doo] /ʌnˈdu/
verb (used with object), undid, undone, undoing.
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.
3.
to bring to ruin or disaster; destroy:
In the end his lies undid him.
4.
to unfasten by releasing:
to undo a gate; to undo a button.
5.
to untie or loose (a knot, rope, etc.).
6.
to open (a package, wrapping, etc.).
7.
Archaic. to explain; interpret.
Origin
900
before 900; Middle English; Old English undōn; cognate with Dutch ontdoen. See un-2, do1
Related forms
undoable, adjective
Can be confused
undo, undue.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for un does

undo

/ʌnˈduː/
verb (mainly transitive) -does, -doing, -did, -done
1.
(also intransitive) to untie, unwrap, or open or become untied, unwrapped, etc
2.
to reverse the effects of
3.
to cause the downfall of
4.
(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 un does

undo

v.

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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