seal

US /siːl/
UK /siːl/
"seal" picture
1.

a device or substance that is used to join two things together so as to prevent them from coming apart or to prevent anything from passing between them

:
The broken seal caused the leak.
Make sure the seal on the container is tight.
2.

a piece of wax, lead, or other material with an individual design stamped into it, attached to a document as a mark of authenticity or used to close a letter or package

:
The king's letter bore his royal seal.
The document was authenticated with an official seal.
3.

a carnivorous marine mammal with flippers, a streamlined body, and a layer of blubber, able to live on land and in water

:
We saw a seal basking on the rocks.
Seals are excellent swimmers.
1.

fasten or close securely, so that air, liquid, or other contents cannot enter or escape

:
Please seal the envelope before mailing it.
The jar was perfectly sealed to keep the contents fresh.
2.

formally certify or approve (something)

:
The deal was sealed with a handshake.
Their fate was sealed when the enemy attacked.