automaticstopper
nounUK /ˌɔːtəˈmætɪk ˈstɒpə/
US /ˌɔːtəˈmætɪk ˈstɑːpər/
A machine part that makes something stop by itself.
The automaticstopper shut off the water when the bucket was full.
OTHER MEANINGS
2. A device that ends a process without a person doing anything.
The automaticstopper turned off the oven after thirty minutes.
3. A safety part that halts a machine when something goes wrong.
The automaticstopper stopped the conveyor belt when the box jammed.
4. A feature that brings a game or program to an end on its own.
The app has an automaticstopper that closes it after an hour.