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English definition of “unknown quantity”

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unknown quantity

noun [C usually singular] uk   us  
C2 a person or a thing whose abilities, powers, or effects are not yet known: The third candidate for the party leadership is a relatively unknown quantity.
Translations of “unknown quantity”
in Chinese (Traditional) 未知數(尚未被人瞭解的人或事物)…
in Chinese (Simplified) 未知数(尚未被人了解的人或事物)…
(Definition of unknown quantity from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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