Meaning

noun an act that makes a previous act of no effect (as if not done)

noun loosening the ties that fasten something

verb cancel, annul, or reverse an action or its effect

originFrom Middle English undoynge, undoand, from Old English undōnde (“undoing”), from Proto-Germanic *andadōndz, present participle of *andadōną (“to undo”). Cognate with Dutch ontdoend (“undoing”).

Etymology from Wiktionary, CC BY-SA 3.0