What part of speech is the word unknown?

The word "unknown" can be a few different parts of speech, depending on how it's used in a sentence:

* Adjective: Describing something that is not known or identified.

* Example: "The killer's motive is unknown."

* Noun: A person, place, or thing that is not known or identified.

* Example: "He vanished into the unknown."

* Past participle: Used as part of a verb phrase to indicate a completed action.

* Example: "The identity of the attacker is unknown."

Let me know if you have a specific sentence in mind, and I can help you determine the part of speech for "unknown" in that context!