adjective
unknown
uh-nohn
adjective
1
Not known, identified, or familiar.
"The cause of the fire is still unknown."
"An unknown singer opened the concert."
noun
1
A variable, typically x, y, or z, whose value must be worked out.
"Solve the equation for the unknown."
2
Something not yet known or understood.
"Many people fear the unknown more than any real danger."
How to Use Unknown
Learner’s notesIn plain EnglishNot identified or not yet found out — as an adjective describing a fact, or a noun for the thing itself.
Common pairings
unknown cause
venture into the unknown
solve for the unknown
Word Forms
more unknown comparative, unknowns plural, most unknown superlative
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The cause of the fire is still _____.
Etymology
From Old English ungecnawen, from "un-" + "known."