[v] remove the outer cover or wrapping of; "Let's unwrap the gifts!"; "undo the parcel"
[v] cause to become loose; "undo the shoelace"; "untie the knot"; "loosen the necktie"
[v] cancel, annul, or reverse an action or its effect; "I wish I could undo my actions"
[v] deprive of certain characteristics
[v] cause the ruin or downfall of; "A single mistake undid the President and he had to resign"