[ uhn-nohn ]
/ ʌnˈnoʊn /


not known; not within the range of one's knowledge, experience, or understanding; strange; unfamiliar.
not discovered, explored, identified, or ascertained: the unknown parts of Antarctica.
not widely known; not famous; obscure: an unknown writer.


a thing, influence, area, factor, or person that is unknown: the many unknowns in modern medicine; The director cast an unknown in the leading role.
Mathematics. a symbol representing an unknown quantity: in algebra, analysis, etc., frequently represented by a letter from the last part of the alphabet, as x, y, or z.

Origin of unknown

First recorded in 1250–1300, unknown is from the Middle English word unknow(e)n. See un-1, known
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for unknown

British Dictionary definitions for unknown

/ (ʌnˈnəʊn) /


not known, understood, or recognized
not established, identified, or discoveredan unknown island
not famous; undistinguishedsome unknown artist
unknown quantity a person or thing whose action, effect, etc, is unknown or unpredictable


an unknown person, quantity, or thing
maths a variable, or the quantity it represents, the value of which is to be discovered by solving an equation; a variable in a conditional equation3y = 4x + 5 is an equation in two unknowns

Derived forms of unknown

unknownness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012