n.

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

   兒子為這個女人神魂顛倒，全然不顧他父母的告誡。

   The red light is a warning sign for stop.

   紅燈是警告停止行進的信號。

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

   希望這件事能成為你的鑑戒。

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

   事先大家毫無察覺的情況下牆塌了。

4. 【古】（解僱；辭職等的）預先通知[U]

a.

1. 警告的；告誡的；引以為戒的
   The policeman fired a warning shot.

   那警察鳴槍警告。

1. warn的動詞現在分詞、動名詞

n.

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