noun
jailer
JAY-ler/ˈdʒeɪlər/
A person responsible for keeping prisoners in a jail.
The jailer stands watch outside the locked cell with keys at her belt.

Etymology
The prison word combines with an agent ending to name its keeper. A jailer is therefore the person responsible for maintaining confinement, rather than someone confined there.
In context
the jailer awoke and saw that every cell door was open and assuming that all the prisoners had escaped he drew his sword
More examples
- A jailer checks each visitor’s identification.
- The prisoner asks the jailer for a blanket.
- Two jailers escort the prisoners back to their cells.
Forms
jailer · jailers
jail noun — A place where prisoners are held.