fire alarm

Short definition from Wiktionary

Noun

1. 1
   An electromechanical or electronic bell, klaxon, chime, horn, speaker, strobe light or other device which warns people in a building of a possible fire or other condition requiring evacuation.
2. 2
   The sound or other warning made by a fire alarm.
3. 3
   An emergency response to a fire by the fire department with manpower and equipment.