undoing

noun

1. the reversing of what has been done; annulling.
2. a bringing to destruction, ruin, or disaster.
3. a cause of destruction or ruin.
4. the act of unfastening or loosing.
5. Psychiatry. an unconscious defense mechanism through which an attempt is made to reverse a psychologically unacceptable act by doing its opposite, usually repetitiously, in order to relieve anxiety.

verb (used with object), un·did, un·done, 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.
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.

noun

1. ruin; downfall
2. the cause of downfalldrink was his undoing

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
3. to cause the downfall of
4. obsolete to explain or solve

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.