- Science and technology of light, and the colloquial term for equipment used to collect and handle light
- A system of lenses, filters, prisms, or mirrors used in electronics to direct, disperse, reflect, or otherwise control light rays.
- The branch of science which deals with all aspects of light, including its nature, properties, generation, detection, measurement, propagation, transmission, control, and applications. Optics may refer strictly to visible radiation, but more generally pertains to electromagnetic radiation whose wavelengths span from microwaves to X-rays, with emphasis on the infrared, visible, and ultraviolet regions.
- The branch of science that deals with vision.
- plural noun optical equipment (such as imaging equipment, optic sights, periscopes, etc.)