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1. An act that makes a previous act of no effect (as if not done)
    
2. Loosening the ties that fasten something
   - untying, unfastening

1. Cancel, annul, or reverse an action or its effect
   "I wish I could undo my actions"
    
2. Deprive of certain characteristics
   "God himself cannot unmake the past or undo what is done";
   - unmake
    
3. Cause the ruin or downfall of
   "A single mistake undid the President and he had to resign"
    
4. Cause to become loose
   "undo the shoelace";
   - untie
    
5. Remove the outer cover or wrapping of
   "undo the parcel";
   - unwrap

Derived forms: undoings

Type of: about-face, alter, change, change by reversal, expose, laxation, loosening, modify, policy change, reversal, reverse, ruin, turn, uncover, volte-face

Antonym: do

Encyclopedia: Undoing