inscrutable

英[ɪn'skruːtəb(ə)l] 美[ɪn'skrʊtəbl]

1. of an obscure nature;: "the new insurance policy is written without cryptic or mysterious terms"; "a deep dark secret"; "the inscrutible workings of Providence"; "in its mysterious past it encompasses all the dim origins of life"- Rachel Carson; "rituals totally mystifying to visitors from other lands"