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English definition of “unknown”

unknown

adjective uk   /ʌnˈnəʊn/ us    /-ˈnoʊn/
B1 not known or familiar: The exact number of people carrying the virus is unknown. As recently as six months ago her name was almost unknown in Britain. Unknown to me, she'd organized a party for my birthday.

unknown

noun uk   /ʌnˈnəʊn/ us    /-ˈnoʊn/
C1 [S] what is not familiar or known: Racism is in some ways just a fear of the unknown. [C] a person, especially a performer or sports player, who is not famous: For her latest film she deliberately chose a cast of unknowns. [C] mainly US something that cannot be guessed at or calculated because so little is known about it: It's the big unknowns that make insurance companies uneasy.
(Definition of unknown from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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