n.

1. 警告；告诫；警报[U][C][（+of）][+to-v]
   The son was so captivated with the woman that he didn't heed his parents' warnings.

   儿子为这个女人神魂颠倒，全然不顾他父母的告诫。

   The red light is a warning sign for stop.

   红灯是警告停止行进的信号。

2. 可引以为戒的事（或人）[C]
   Let this be a warning to you.

   希望这件事能成为你的鉴戒。

3. 征候；前兆[C]
   The wall caved in without the slightest warning.

   墙在没有一点征兆的情况下塌了。

4. 【古】（解雇、辞职等的）预先通知[U]

a.

1. 警告的；告诫的；引为戒的
   The policeman fired a warning shot.

   那警察鸣枪警告。

n.

1. a statement or event that warns or serves as a cautionary example.
2. cautionary advice.
3. advance notice.