* Noun: This is the most common usage, referring to a closed space or a thing that encloses something else. For example: "The animals were kept in a secure enclosure."
* Verb: This usage means "to close in or surround," often with a fence or wall. For example: "The park was enclosed by a high fence."
* Adjective: This is a less common usage, meaning "closed in or surrounded." For example: "The enclosure was filled with flowers."
So, to determine the part of speech, you'll need to look at how it's used in the specific sentence.