undo (v.)youdaoicibaDictYouDict[undo 词源字典]
Old English undon "to unfasten and open" (a window or door), "to unfasten by releasing from a fixed position; to cancel, discharge, abrogate, reverse what has been done, put back in a former condition; bring to ruin, destroy," from un- (2) "opposite of" + do (v.). Related: Undone; undoing.[undo etymology, undo origin, 英语词源]