noun

• (optics) An object, usually made of glass, that focuses or defocuses the light that passes through it.
  "Not long ago, it was difficult to produce photographs of tiny creatures with every part in focus. That’s because the lenses that are excellent at magnifying tiny subjects produce a narrow depth of field."
• (geometry) A convex shape bounded by two circular arcs, joined at their endpoints, the corresponding concave shape being a lune.
• (biology) A genus of the legume family; its bean.
• (anatomy) The transparent crystalline structure in the eye.
  "The single-imaging optic of the mammalian eye offers some distinct visual advantages. Such lenses can take in photons from a wide range of angles, increasing light sensitivity. They also have high spatial resolution, resolving incoming images in minute detail."

verb

• (transitive, cinematography) To film, shoot.
  "It’s set in an anonymous, upper-middle-class suburb, lensed in the generic gunmetal gray that will one day appear as dated as the fuzzy outlines of ’80s direct-to-video horror movies."
• (geology) To become thinner towards the edges.