adjective
- 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.
noun
- 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.
adjective
- 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
noun
- 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
adj.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.