prealarm
/ˈpriːˌɑːrm/Definitions
1. noun
A warning given before an alarm sounds, especially to alert people to prepare for a potential emergency or danger.
“The fire department received a prealarm from the building’s security system before the actual fire alarm sounded.”
2. verb
To give a warning before an alarm sounds, especially to alert people to prepare for a potential emergency or danger.
“The security team prealarmed the building to evacuate everyone before the storm hit.”