The term "invisible" refers to something that cannot be seen by the naked eye. This can apply to various phenomena, such as air, which is all around us but not visible. Other examples include ultraviolet light and radio waves, which are forms of energy that exist outside the visible spectrum. Invisibility can also describe objects or beings that are hidden from view, like a camouflaged animal blending into its environment. In literature and film, characters like superheroes may possess the ability to become invisible, adding an element of mystery and intrigue to their stories.