: 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
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
Ca Wildfire Bot, Sacbee.com, 24 May 2025
According to Lesperance, most people don't like to move, abandoning their familiar life for one that is widely unknown.
—Giulia Carbonaro, MSNBC Newsweek, 24 May 2025
Eliza Brooke, Vox, 23 May 2025
Travel had a different level of freedom and many more unknowns along the way.
—Michael Schaub, Oc Register, 20 May 2025
See All Example Sentences for unknown
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Adjective
At this time, the containment status is unknown and the cause of the fire remains undetermined.
—Ca Wildfire Bot, Sacbee.com, 24 May 2025
According to Lesperance, most people don't like to move, abandoning their familiar life for one that is widely unknown.
—Giulia Carbonaro, MSNBC Newsweek, 24 May 2025
Noun
In a world of unknowns, simple and concrete statements are a comfort — and the urge to seek out other people’s advice is painfully, sweetly human.
—Eliza Brooke, Vox, 23 May 2025
Travel had a different level of freedom and many more unknowns along the way.
—Michael Schaub, Oc Register, 20 May 2025
See All Example Sentences for unknown
Cite this Entry
“Unknown.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unknown. Accessed 29 May. 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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