• unkownunkown,
• uknownunkown

• unknown incident,
• none known,
• noun known,
• none knowns,
• no known,
• unknown,
• unknowns,
• unknown uncommon,
• unknown specific,
• no knowns,
• unknown pruning,
• unknown attunement,
• unknown known,
• unknown significant.

The adjective form of the word "unknown" is "unknown".

There is no plural form for the word "unknownunknown" as it is already plural.

The singular form of the word "unknownunknown" is "unknown"