unknown

Universal Words adjective, noun adjective 1 ~ (to sb) not known or identified: a species of insect previously unknown to science * He was trying, for some unknown reason, to count the stars. * The man's identity remains unknown. 2 (of people) not famous or well known: an unknown actor / artist / writer * The author is virtually unknown outside Poland. 3 never happening or existing: The disease is as yet unknown in Europe (= there have been no cases there). * It was not unknown for people to have to wait several hours (= it happened sometimes). IDIOMS an unknown quantity a person or thing whose qualities or abilities are not yet known unknown to sb without the person mentioned being aware of it: Unknown to me, he had already signed the agreement. noun 1 (the unknown) [sing.] places or things that are not known about: a journey into the unknown * a fear of the unknown 2 [C] a person who is not well known: A young unknown played the leading role. 3 [C] a fact or an influence that is not known: There are so many unknowns in the proposal. 4 [C] (mathematics) a quantity that does not have a known value: X and Y in the equation are both unknowns.