: not known or not well-known
also
: having an unknown value
an unknown quantity
1
: one that is not known or not well-known
especially
: a person who is little known (as to the public)
2
: something that requires discovery, identification, or clarification: such as
a
: a symbol (such as x, y, or z) in a mathematical equation representing an unknown quantity
b
: a specimen (as of bacteria or mixed chemicals) required to be identified as an exercise in appropriate laboratory techniques
Synonyms
Examples of unknown in a Sentence
Adjective
a disease of unknown cause
Much remains unknown about his early life.
Her music was previously unknown outside of Asia.
An unknown number of cases go unreported.
The victim's attacker was unknown to her.
For some unknown reason, my computer crashed.
a book of unknown poems
Noun
explorers venturing off into the unknown
A fear of the unknown kept her from changing jobs.
The director cast an unknown in the lead role.
We're facing too many unknowns.
Recent Examples on the Web
Spencer Kornhaber, The Atlantic, 25 Dec. 2024
Most human cases have occurred in people exposed to cattle or poultry, while the source of infection was unknown in two cases and one case was linked to a different infected animal.
—Andy Biggs, Newsweek, 24 Dec. 2024
Seth Emerson, The Athletic, 24 Dec. 2024
Even though the law technically goes into effect on Jan. 1, 2025, there are still a lot of unknowns surrounding it.
—Barnini Chakraborty, Washington Examiner - Political News and Conservative Analysis About Congress, the President, and the Federal Government, 24 Dec. 2024
See all Example Sentences for unknown 
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Adjective
Rather than try to crack the case with backstory providing psychological cause and effect, A Complete Unknown just lets Dylan be … unknown.
—Spencer Kornhaber, The Atlantic, 25 Dec. 2024
Most human cases have occurred in people exposed to cattle or poultry, while the source of infection was unknown in two cases and one case was linked to a different infected animal.
—Andy Biggs, Newsweek, 24 Dec. 2024
Noun
If the first matchup in 2017 felt like a battle of two unknowns and the second in 2019 felt like Georgia making The Leap while Notre Dame was trying to keep up but not quite pulling it off, what does the third game feel like to you?
—Seth Emerson, The Athletic, 24 Dec. 2024
Even though the law technically goes into effect on Jan. 1, 2025, there are still a lot of unknowns surrounding it.
—Barnini Chakraborty, Washington Examiner - Political News and Conservative Analysis About Congress, the President, and the Federal Government, 24 Dec. 2024
See all Example Sentences for unknown
Articles Related to unknown
Dictionary Entries Near unknown
Cite this Entry
“Unknown.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unknown. Accessed 2 Jan. 2025.
Copy CitationKids Definition
unknown
1 of 2 adjective
un·known
ˌən-ˈnōn 
: not known
also
: having an unknown value
an unknown quantity
unknown
2 of 2 noun1
: something that is unknown
2
: a symbol (as x, y, or z) representing a quantity whose value is unknown
an equation with two unknowns
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