Enclose (verb):
1. To put something inside an envelope: Please enclose a cheque with your oder. Please find enclosed an agenda for the meeting.
2. to surround something, especially with a fence or wall, in order to make it separate (usually passive): The pool area is enclosed by a six-foot wall. An enclosed area.

Enclosure (noun):
1. An area surrounded by a wall or fence and used for a particular purpose (Cercado).
2. something that is put inside an envelope with a letter (Anexo).

Fonte: Longman Dict of Contemporary English