noun

1. Something enclosed, i.e. inserted into a letter or similar package.

   “There was an enclosure with the letter — a photo.”

2. The act of enclosing, i.e. the insertion or inclusion of an item in a letter or package.

   “The enclosure of a photo with your letter is appreciated.”

3. An area, domain, or amount of something partially or entirely enclosed by barriers.

   “He faced punishment for creating the fenced enclosure in a public park.”