enclosure
n. countablen. an area that is surrounded by a fence or wall to keep things inside. It can also mean something extra that you put inside an envelope with a letter.
n. an area of land or a space that is surrounded by a barrier; also refers to a document or object included within an envelope or package.
The lions live in a large enclosure at the zoo.
Please check the enclosure at the bottom of the letter for the signed contract.
The archaeological team discovered a stone enclosure that likely served as a communal gathering space for the ancient settlement's inhabitants.
From Middle English enclosure, from Old French enclosure, from enclore, from Latin inclūdere, inclūdō, from in- (“in”) + claudō (“to shut”), ultimately from Proto-Indo-European *kleh₂u- (“key, hook, nail”). Alike to inclusion.
Commonly used in business correspondence to refer to attachments; in physical contexts, it implies a clearly defined boundary.