Sealer
(noun)
A device, substance, or person that is used to close or fasten something, typically to prevent leakage or spoilage.
Origin:
From seal (a device or substance used to close or fasten something) + -er (one who does or performs).
Examples:
- The sealer was applied to the concrete surface to protect it from moisture damage.
- The fisherman used a sealer to waterproof his boat.