: 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
Letters To The Editor, The Mercury News, 15 Nov. 2024
The lack of regulation may help explain why the state has the nation’s lowest autopsy rate in child deaths attributed to unnatural or unknown causes — a category that includes suicides, homicides, crashes, drownings, overdoses and sudden infant deaths.
—Audrey Dutton, ProPublica, 11 Nov. 2024
Dieter Kurtenbach, The Mercury News, 18 Nov. 2024
Life beyond Earth is among the greatest unknowns in science.
—Joel Achenbach, arkansasonline.com, 20 Oct. 2024
See all Example Sentences for unknown 
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Adjective
To begin with, having only 107 days to run a presidential campaign would be a tall order for any politician, let alone a relatively unknown Black woman from what is arguably the most liberal state in the country.
—Letters To The Editor, The Mercury News, 15 Nov. 2024
The lack of regulation may help explain why the state has the nation’s lowest autopsy rate in child deaths attributed to unnatural or unknown causes — a category that includes suicides, homicides, crashes, drownings, overdoses and sudden infant deaths.
—Audrey Dutton, ProPublica, 11 Nov. 2024
Noun
This campaign has all the hallmarks of a lost season, leading to a great unknown in future years.
—Dieter Kurtenbach, The Mercury News, 18 Nov. 2024
Life beyond Earth is among the greatest unknowns in science.
—Joel Achenbach, arkansasonline.com, 20 Oct. 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 1 Dec. 2024.
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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