What does unknown mean?
Unknown is an adjective meaning that something has not been identified, understood, or discovered. It can describe a person whose identity or background is unclear, a cause that remains undiscovered, a quantity that cannot be calculated, or a result that cannot be predicted. The expression is deliberately broad and often conveys an absence of reliable information rather than a specific explanation. As a noun, an unknown is a person, thing, or issue whose nature is not known; the unknown can also refer more broadly to everything beyond human comprehension. Unknown frequently appears with phrases such as unknown quantity, unknown source, and remain unknown. In some contexts, especially in journalism and scientific writing, it expresses careful neutrality: a report may say that the cause is unknown until evidence establishes it. The word is useful because it marks the precise limit of what is presently known without implying that the question has been permanently settled.
Not known, identified, understood, or discovered; not familiar or previously established.
"The origin of the word is unknown."
This is the dominant modern use. It may modify people, objects, causes, quantities, outcomes, or abstract matters.
A person, thing, issue, or outcome whose identity or nature is not known.
"The young musician was quickly promoted from an unknown to a major performer."
The definite form the unknown can mean the realm of what is beyond human knowledge; the plural unknowns refers to unresolved questions or uncertain factors.
Used when referring to multiple unresolved matters, unidentified people or things, or uncertain factors affecting a situation.
"The team acknowledged several unknowns before beginning the investigation."
Unknown is not merely missing information: it marks the boundary where curiosity begins.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does unknown come from?
The word formed in Middle English by combining the negative prefix un- with known. Its base, know, comes from Old English cnāwan, while the related noun knowledge also preserves this Germanic root. In English, acknowledge was later formed with the Latin-derived prefix acknowledge- plus the same English root, showing how the idea of knowing has generated several related words. The modern adjective unknown has long been used for both unidentified things and matters beyond human understanding.
Related word forms
How unknown is actually used
As an adjective, unknown is neutral and widely used in both formal and informal registers. As a noun, an unknown commonly refers to an unidentified person or thing, while the unknown often means what lies beyond human knowledge. The plural unknowns is used for matters that remain unresolved.
Easily confused with unknown
An unknown thing is not known or identified, whereas an unfamiliar thing may be known to exist but be strange or new to someone.
Unknown means not known or understood, while unidentified means that a person, object, or event has not been specifically identified.