Alarm is a feeling of fear or anxiety that something unpleasant or dangerous might happen.

If something alarms you, it makes you afraid or anxious that something unpleasant or dangerous might happen.

An alarm is an automatic device that warns you of danger, for example by ringing a bell.

An alarm is the same as an alarm clock .

If you say that something sets alarm bells ringing, you mean that it makes people feel worried or concerned about something.

If you raise the alarm or sound the alarm, you warn people of danger.