stopper
UK: ˈstɒpə | US: ˈstɑːpər
n. an object used to close or seal an opening
vt. to close or secure with a stopper
The word "stopper" combines the verb "stop" (from Old English stoppian, meaning "to block or close") with the agentive suffix "-er," which denotes a person or thing that performs an action. Originally used in Middle English, it literally means "something that stops." The logic is straightforward: a stopper is an object designed to halt or block passage, such as a cork in a bottle.
She pushed the rubber stopper into the test tube.
The wine bottle’s stopper was made of cork.
He forgot to use a stopper, and the water leaked out.
The mechanic installed a stopper to prevent oil leakage.
This jar requires a tight-fitting stopper to keep the contents fresh.