* Adjective: This is the most common usage. It describes something as relating to or characteristic of a nation.
* Example: "The national anthem was played."
* Noun: It can be a noun referring to a nation or people.
* Example: "The interests of the nation must be considered."
* Adverb: This is less common, but it can be used to modify a verb, adjective, or another adverb, meaning "on a national level."
* Example: "The company operates nationally."
So, the answer depends on the context.