from The American Heritage® Dictionary of the English Language, 4th Edition
- transitive v. To reverse or erase; annul: impossible to undo the suffering caused by the war.
- transitive v. To untie, disassemble, or loosen: undo a shoelace.
- transitive v. To open (a parcel, for example); unwrap.
- transitive v. To cause the ruin or downfall of; destroy.
- transitive v. To throw into confusion; unsettle.
- transitive v. Obsolete To solve or interpret; unravel.
- intransitive v. To come open or unfastened.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To reverse the effects of an action. syn.
- v. To unfasten. ant. syn.
- v. to be heading for or to cause a downfall
from the GNU version of the Collaborative International Dictionary of English
- transitive v. To reverse, as what has been done; to annul; to bring to naught.
- transitive v. To loose; to open; to take to piece; to unfasten; to untie; hence, to unravel; to solve.
- transitive v. To bring to poverty; to impoverish; to ruin, as in reputation, morals, hopes, or the like.
from The Century Dictionary and Cyclopedia
- To leave unperformed or unexecuted: usually in opposition with do.
- To put back into a former condition; reverse, as something which has been done; annul; bring to nought.
- To untie or unfasten; unloose; unfix; open.
- To find the answer or explanation of; solve.
- To bring ruin or distress upon; ruin the morals, character, reputation, or prospects of; destroy; annihilate; spoil; ruin.
- To reveal; disclose; unfold; explain.
- To be too much for the power of; baffle.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- v. deprive of certain characteristics
- v. cancel, annul, or reverse an action or its effect
- v. cause to become loose
- v. cause the ruin or downfall of
- v. remove the outer cover or wrapping of
un- + do (Wiktionary)