undo /ˈʌnˈdu:/ vt. (undid /ˈʌnˈdid/, undone /ˈʌnˈdʌn/) 1. 解开，松开：undo a knot(button) 解开结子（钮扣）；undo a parcel 打开包裹 2.取消，撤消；毁掉： undo his post 撤消他的职位 The fire undid the work of six months. 这把火把六个月的工作全部烧光了。