1
a
: not known
It was a world and life, a way of being, utterly unknown to me.—Avi
An unknown number of cases go unreported.
For some unknown reason, the computer crashed.
b
: not well-known
an unknown writer/artist
When he left, he had been unknown. Now he was famous.—E. B. White
2
: having an unknown value
an unknown quantity
1
a
: one that is not known or not well-known
especially
: a person who is little known (as to the public)
The director cast an unknown in the lead role.
b
the unknown
: a place, situation, or thing that is not known or understood
explorers venturing into the unknown
c
: something that is not known or not yet discovered
There are too many unknowns to go forward with the project.
2
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
Cite this Entry
“Unknown.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unknown. Accessed 8 Aug. 2026.
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