reliefguard
nounUK /rɪˈliːfɡɑːd/
US /rɪˈliːfɡɑːrd/
A relief guard is a person who takes over guarding a place so the first guard can rest.
The relief guard arrived at midnight to watch the gate while the other guard slept.
OTHER MEANINGS
2. A protective pad or shield that eases pressure or pain.
He wore a reliefguard on his knee to soften the blow.
3. A device that protects against sudden pressure or strain.
The reliefguard valve kept the pipe from bursting.
4. A person who steps in to help someone during a hard time.
She acted as a reliefguard for her tired friend during the long night.