Unexplored is an adjective.
If unexplored land was explored then it would no longer be unexplored land, and that is why it is impossible to explore unexplored land.
A sentence using 'unexplored' would be: Long ago Michigan was unexplored. Mary's attic is so full of things that it has remained unexplored for many years.
An unexplored area inhabited by one's enemy may be called hostile territory.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
what part of speech is beneath
adverb
The part of speech for "explicit" is an adjective.
The part of speech for "lecturer" is a noun.
The part of speech for "rapid" is an adjective.
The part of speech of "came" is a verb.