Enclosure (noun)

1. An area of land that is enclosed by a fence or wall.
2. The action or process of enclosing an area of land.
3. A space or area that is enclosed, such as an enclosure in a building or an enclosure in an email.

Origin:

Late middle english: from old french enclos, from enclore "enclose", from en- "in" + clore "close".

Examples:

1. A large enclosure for cattle.
2. The enclosure of common land.
3. The enclosure of the courtyard.
4. The enclosure of the email contained additional information.
5. An enclosure for the pool equipment.