[ 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.

Nearby words

  1. unknit,
  2. unknot,
  3. unknowable,
  4. unknowing,
  5. unknowingly,
  6. unknown quantity,
  7. unknown soldier,
  8. unlace,
  9. unlade,
  10. unladen

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 Formsunknownness, 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

Word Origin and History for unknown



c.1300, "strange, unfamiliar" (of persons, places), from un- (1) "not" + past participle of know. Cf. Old English ungecnawen. In reference to facts, attested from early 14c. The noun meaning "unknown person" is recorded from 1590s.

Online Etymology Dictionary, © 2010 Douglas Harper