: 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
Michael McCann, Sportico.com, 1 July 2024
Today, both drawings are displayed on 14 billboards in the Orlando area in an attempt to reunite them with their creators, whose last names are unknown.
—Alissa Gary, Orlando Sentinel, 29 June 2024
Tribune News Service, The Mercury News, 19 June 2024
Our five vintage Vanagons pass through several seasons—from bluebird skies to dense downpours—along our journey toward what to many travelers is still a great unknown.
—Krista Simmons, Sunset Magazine, 10 June 2024
See all Example Sentences for unknown 
Adjective
Whether the economics work for teams is unknown, but compromise broadcasting arrangements could be in the cards.
—Michael McCann, Sportico.com, 1 July 2024
Today, both drawings are displayed on 14 billboards in the Orlando area in an attempt to reunite them with their creators, whose last names are unknown.
—Alissa Gary, Orlando Sentinel, 29 June 2024
Noun
Here’s a rundown of key results: Cole wins easily in Oklahoma
In Oklahoma’s 4th District, Republican Rep. Tom Cole, the powerful chairman of the House Appropriations Committee, easily defeated four fellow Republicans, including a political unknown who loaned his campaign more than $5 million.
—Tribune News Service, The Mercury News, 19 June 2024
Our five vintage Vanagons pass through several seasons—from bluebird skies to dense downpours—along our journey toward what to many travelers is still a great unknown.
—Krista Simmons, Sunset Magazine, 10 June 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 7 Jul. 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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