inscrutable

Adjective

Synonyms: cryptic cryptical deep mysterious mystifying

WordNet 3.0

Adjective (1)

of an obscure nature“the new insurance policy is written without cryptic or mysterious terms”“a deep dark secret”“the inscrutable 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”Synonyms: cryptic cryptical deep mysterious mystifying

Webster's Dictionary (GCIDE)

Inscrutable \In*scru"ta*ble\, a. [L. inscrutabilis : cf. F. inscrutable. See In- not, and Scrutiny.] Unsearchable; incapable of being searched into and understood by inquiry or study; impossible or difficult to be explained or accounted for satisfactorily; obscure; incomprehensible; as, an inscrutable design or event. [1913 Webster]

'T is not in man To yield a reason for the will of Heaven Which is inscrutable. --Beau. & Fl. [1913 Webster]

Waiving a question so inscrutable as this. --De Quincey. [1913 Webster]