What is the meaning of Iris in camera lenses?

It is a component of camera lenses. It is an expandable circular opening which allow light to pass through it inside the camera. It allow light in varying levels of illumination. If it is opened maximum as much as it can, maximum light is passed through it. Inversely, if it is closed, minimum amount of light is passed to the camera. It's opening is measured in f-stop like f/4.6, f/1.5, etc. f/1.4 is the widest opening of iris. It's opening is controlled either manually or automatically.