responder
/rɪˈspɑndər/
noun
- A person who answers or reacts to something, especially in an official or emergency capacity.
- The first responder arrived at the scene within minutes.
- The survey responder completed all the questions online.
- She works as an emergency responder for the local fire department.
- A device or system that sends a signal in reply to another signal.
- The security system's responder sent an alert to the control room.
- Each satellite has a responder that activates when contacted.
- The radio responder automatically transmitted our location.