alarum

n.an automatic signal (usually a sound) warning of danger

同义词：alarmalertwarning signal

1. The sudden alarum startled the soldiers, signaling the approach of the enemy.
   突然的警报使士兵们惊慌，标志着敌人的逼近。
2. In Shakespeare's plays, the sound of an alarum often indicates a turning point in the action.
   在莎士比亚的戏剧中，警报的声音常常标志着情节的转折点。