sealer
nounUK /ˈsiːlə/
US /ˈsiːlər/
A sealer is something that closes a container tightly so nothing can get out.
She used a sealer on the jar to keep the jam fresh.
OTHER MEANINGS
2. A substance painted or spread on a surface to protect it from water or damage.
We put a sealer on the wooden deck before winter.
3. A person whose job is to close or stamp official documents.
The sealer stamped the certificate with the official mark.
4. A machine or device that seals packages or bags.
The factory uses a heat sealer to close each plastic bag.