To seal an opening, so as to prevent the entry of draughts.
That prevents the entry of draughts.
To enclose something in, or as if in, a capsule.
To enclose data in packets that can be transmitted using a given protocol.
To epitomize something by expressing it as a brief summary.
To enclose objects in a common interface in a way that makes them interchangeable, and guards their states from invalid changes.