un·do / ˌənˈdoō/ • v. (-does / -ˈdəz/ ; past -did ; past part. -done ) [tr.] 1. unfasten, untie, or loosen (something): the knot was difficult to undo. 2. cancel or reverse the effects or results of (a previous action or measure): there wasn't any way Evelyn could undo the damage. ∎  cancel (the last one or more commands executed by a computer). 3. formal cause the downfall or ruin of: Iago's hatred of women undoes him.• n. Comput. a feature of a computer program that allows a user to cancel or reverse the last one or more commands executed.

undo A feature of some applications that allows the user to reverse the effect of the last action or actions. This allows recovery from unintentional actions, and could prevent major damage resulting from a very simple but incorrect command. See also user-friendly, rollback.

undo
A. unfasten;

B. annul, make of no effect; bring to nought, destroy, ruin OE.;

C. † expound XIII. OE. undōn = (M)Du. ontdoen, OHG. intuon; see UN-2, DO1.
Hence undone ruined, destroyed XIV.