lacking enlightenment or knowledge or culture; "this benighted country"; "benighted ages of barbarism and superstition"; "the dark ages"; "a dark age in the history of education"
overtaken by night or darkness; "benighted (or nighted) travelers hurrying toward home"
impossible or difficult to perceive by the mind or senses; "an imperceptible drop in temperature"; "an imperceptible nod"; "color is unperceivable to the touch"
increased pressure in the eyeball due to obstruction of the outflow of aqueous humor; damages the optic disc and impairs vision (sometimes progressing to blindness)