Synonyms and related words :
Greek to one, able, ambiguous, arcane, beyond understanding, cabalistic, enigmatic, impenetrable, inarticulate, incalculable, incognizable, incoherent, incomprehensible, inscrutable, mysterious, mystic, numinous, past comprehension, puzzling, rambling, sealed, strange, unapparent, unapprehended, unascertained, unbeknown, uncharted, unclassified, unconnected, undisclosed, undiscoverable, undiscovered, undivulged, unexplained, unexplored, unexposed, unfamiliar, unfathomable, unfathomed, ungraspable, unguessed, unheard, unheard-of, unidentified, unimaginable, unintelligible, uninvestigated, unknown, unperceived, unplumbed, unrevealed, unsearchable, unsuspected, untouched, virgin