It's primarily a noun, referring to the natural satellite of the Earth.
However, there are some informal or slang uses where "moon" could be used as a verb:
* "To moon" - This means to expose one's backside to someone, often in a rude or humorous way. This is a slang term and not considered formal language.
* "To moonlight" - This means to have a second job in addition to one's main job. This usage is more common and generally accepted.
So, while "moon" isn't a standard verb, it can be used in certain situations.