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adj.
beyond and outside the ordinary range of human experience or understanding; "philosophers...often explicitly reject the notion of any transcendent reality beyond thought...and claim to be concerned only with thought itself..."- W.P.Alston; "the unknowable mysteries of life"
adj.
(usually used with `to') occurring or existing without the knowledge of; "a crisis unbeknown to me"; "she had been ill for months, unbeknownst to the family"