: 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
Democrat-Gazette Staff From Wire Reports, arkansasonline.com, 19 Apr. 2024
The structural condition of the pier was unknown at the time of the collapse.
—Kelly Meyerhofer, Journal Sentinel, 19 Apr. 2024
See all Example Sentences for unknown 
Adjective
The details of the blast in Isfahan are unknown, according to Fars, but the city -- home to several military bases and facilities -- is believed to have been one of several launch sites for Iran's April 13 attack.
—Democrat-Gazette Staff From Wire Reports, arkansasonline.com, 19 Apr. 2024
The structural condition of the pier was unknown at the time of the collapse.
—Kelly Meyerhofer, Journal Sentinel, 19 Apr. 2024
See all Example Sentences for unknown
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'unknown.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
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Cite this Entry
“Unknown.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unknown. Accessed 3 May. 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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