Alarm refers to the set of biologic reactions indicating imminence of major hazard.
See also:
"Alarm" is in the CPC Code "8523"
  Alarm monitoring services
"Alarm" is in the UNSPSC Code "46171604"
  Alarm systems
"Alarm" is in the NAICS Code "23821"
  (Inofficial Code)
  Alarm system (e.g., fire, burglar), electric, installation only
"Alarm" is in the HS Code "9105.11"
  - -- Electrically operated
  Alarm clocks, electrically operated
Other /More definition:
Alarm refers to the set of biologic reactions indicating imminence of major hazard.