(informal) Astronomy using observations using telescopes and recording media that capture visible light. / (astronomy) Astronomy using infrared, visible, and/or ultraviolet wavelengths.

The inflammation of the optic nerve that may cause a complete or partial loss of vision.

plural of optical isomer

(computer hardware) A drive that reads optical media.

(astronomy) A star that appears as a double due to an optical illusion; in reality, the stars may be far apart from each other.

Op art.

(neuroanatomy) Each of the second pair of cranial nerves that carry visual information from the retina to the brain.

(telecommunications) A switch that can selectively change signals between optical fibers or integrated optical circuits.

(chemistry, of a crystal or compound) Exhibiting optical activity.

Alternative spelling of fibre optic