able accepted believed credited enigmatic incalculable incognizable mysterious puzzling received sealed strange trusted unapparent unapprehended unascertained unbeknown uncharted unclassified uncontested undisclosed undiscoverable undiscovered undisputed undivulged undoubted unexplained unexplored unexposed unfamiliar unfathomed unheard unheard-of unidentified uninvestigated unknowable unknown unperceived unplumbed unquestioned unrevealed untouched virgin