security alarm

Meaning

A device that makes a loud noise or sends a warning signal when there is unauthorized entry, danger, or when a restricted area is breached. In travel, you often encounter them at airport security gates, hotel emergency exits, or on luggage scanners.

Examples

• My metal belt buckle set off the security alarm at the airport checkpoint.

  My metal belt buckle set off the security alarm at the airport checkpoint.

• Please do not open that door, or you will trigger the security alarm.

  Please do not open that door, or you will trigger the security alarm.

• The hotel's security alarm went off in the middle of the night by mistake.

  The hotel's security alarm went off in the middle of the night by mistake.

• The security alarm is designed to detect any unauthorized entry into the terminal.

  The security alarm is designed to detect any unauthorized entry into the terminal.

• I accidentally touched the sensor and activated the security alarm.

  I accidentally touched the sensor and activated the security alarm.

Common Mistakes

• ✗ I opened the door and opened the security alarm.

  ✓ I opened the door and set off the security alarm.

  We use verbs like 'set off', 'trigger', or 'activate' for alarms, not 'open'.

• ✗ The security alarm was ringing.

  ✓ The security alarm was going off.

  While 'ringing' is understood, native speakers almost always say an alarm is 'going off' or 'sounding'.

Related Expressions

Practice

• I forgot I had keys in my pocket and set off the ___.

  💡 The loud warning device at the security checkpoint.

  Show answer

  security alarm

• Don't push that emergency bar unless there is a fire, or the ___ will sound.

  💡 An electronic alert system.

  Show answer

  security alarm