A lens is:

• a part of the eye
• an optical device that may be used in a camera or in a telescope; see lens (optics).
• the genus of the lentil
• a science-fictional alien device in E. E. Smith's Lensman series, which gives its bearer telepathic and other abilities.
• a gravitational lens

There are also places called Lens:

• Lens, Pas-de-Calais, France
• Lens, Belgium
• Lens , Valais, Switzerland

as well as Racing Club de Lens, a football club from the French city listed above.