adj

• (relational) Of, or relating to the eye or to vision.
  "The moon, whose orb / Through optic glass the Tuscan artist views."
• (optics, relational) Of, or relating to optics or optical instruments.

noun

• (archaic, humorous) An eye.
  "The difference is as great between / The optics seeing, as the object seen."
• (optics) A lens or other part of an optical instrument that interacts with light.
  "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."
• (trademark in UK) A measuring device with a small window, attached to an upside-down bottle, used to dispense alcoholic drinks in a bar.
  "They were neatly lined up on three shelves between the optics of martini, vodka, whisky and gin."