vt.

1. 解開，打開；使鬆開；脫去（衣服等）
   He undid the parcel.

   他打開了包裹。

2. 取消，消除；使失敗；使復舊
   What's done cannot be undone.

   覆水難收。

3. 破壞，敗壞（成果、名譽等）；毀滅[H]
   He has undone the good work of his predecessor.

   他已毀了他前任取得的良好成就。

4. 擾亂，使不安

v.

1. unfasten, untie, or loosen.
2. cancel or reverse the effects or results of (a previous action or measure).
3. formal cause the downfall or ruin of.