: 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
Raja Krishnamoorthi, Newsweek, 13 Mar. 2025
No injuries have been reported and the cause of the fire is unknown.
—Katie Langford, The Denver Post, 13 Mar. 2025
Judy D. Olian, TIME, 13 Mar. 2025
In reality, every era has been defined by its own set of unknowns.
—Margie Warrell, Forbes, 12 Mar. 2025
See All Example Sentences for unknown
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Adjective
At the moment, everyone is on standby as the severity of Flagg's ankle injury is unknown.
—Raja Krishnamoorthi, Newsweek, 13 Mar. 2025
No injuries have been reported and the cause of the fire is unknown.
—Katie Langford, The Denver Post, 13 Mar. 2025
Noun
In a world of increasing unknowns, the inoculating effects of a college degree can be the difference between weathering a storm versus being swept away by it.
—Judy D. Olian, TIME, 13 Mar. 2025
In reality, every era has been defined by its own set of unknowns.
—Margie Warrell, Forbes, 12 Mar. 2025
See All Example Sentences for unknown
Articles Related to unknown
Cite this Entry
“Unknown.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unknown. Accessed 23 Mar. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share