stopper
nounUK /ˈstɒp.ər/
US /ˈstɑː.pɚ/
A stopper is a thing you put in a bottle to close it.
She pushed the stopper into the bottle so the juice would not spill.
OTHER MEANINGS
2. A person or thing that stops something from happening or continuing.
The new rules acted as a stopper on wasteful spending.
3. In sports, a player who is very good at blocking the other team.
Their goalkeeper is a great stopper and saved many goals.
4. A device that stops a machine or flow.
He turned the stopper to shut off the water.