without being seen

capable of being seen; or open to easy view

the quality of not being perceivable by the eye

the quality of not being perceivable by the eye

secret or hidden; not openly practiced or engaged in or shown or avowed

impossible or difficult to perceive by the mind or senses

made invisible by means of protective coloring

not accessible to view

having or employing wavelengths longer than light but shorter than radio waves; lying outside the visible spectrum at its red end

giving no light

not resulting in vision