When something alarms you, it suddenly makes you worried or afraid that danger might be near. If you hear a strange noise in the night or see dark storm clouds racing toward you, you feel alarmed because these signals suggest trouble might be coming.

An alarm is also a device that warns you about danger or wakes you up. A fire alarm makes a loud noise when it detects smoke. A burglar alarm sounds when someone tries to break into a building. Most people use an alarm clock to wake up in the morning, though waking to an alarm feels quite different from waking naturally.

The word suggests urgency and the need for quick attention. When you sound the alarm, you're warning others about danger, like Paul Revere riding through colonial towns shouting that British troops were coming. Scientists might raise the alarm about a new disease, meaning they're urgently trying to get people to pay attention before the problem gets worse.

Not every worry deserves alarm. Being alarmed means you sense real danger or serious trouble, not just mild concern. If your friend seems alarmingly pale, they look so unwell that you're genuinely worried about them.