en.wikipedia.org/wiki/There_are_known_knowns

"There are known knowns" is a phrase from a response United States Secretary of Defense ... But there are also unknown unknowns – the ones we don't know we don't know. And if one looks throughout the history of our country and other free ...

www.merriam-webster.com/dictionary/unknown

Unknown definition is - not known or not well-known; also : having an unknown value. How to use unknown in a sentence.

www.merriam-webster.com/dictionary/the%20unknown

The unknown definition is - a place, situation, or thing that is not known about or understood : a situation that one is unfamiliar with. How to use the unknown in a ...

www.dictionary.com/browse/unknown

Unknown definition, not known; not within the range of one's knowledge, experience, or understanding; strange; unfamiliar. See more.

dictionary.cambridge.org/us/dictionary/english/unknown

unknown meaning: 1. not known or familiar: 2. what is not familiar or known: 3. a person, especially a performer or sports player, who is not famous: .

www.thesaurus.com/browse/unknown

Synonyms for unknown at Thesaurus.com with free online thesaurus, antonyms, and definitions. Find descriptive alternatives for unknown.

www.macmillandictionary.com/us/dictionary/american/unknown_2

Define unknown (noun) and get synonyms. What is unknown (noun)? unknown ( noun) meaning, pronunciation and more by Macmillan Dictionary.

www.collinsdictionary.com/us/dictionary/english/unknown

Unknown definition: If something is unknown to you, you have no knowledge of it. | Meaning, pronunciation, translations and examples.

www.thefreedictionary.com/unknown

Define unknown. unknown synonyms, unknown pronunciation, unknown translation, English dictionary definition of unknown. adj. 1. Not known; unfamiliar : a ...