- adjective referring to the eyes or to eyesight
- adjective relating to or making use of light
- Of, pertaining to, or utilizing visible light, vision, or optics. Visible light spans from approximately 750 nanometers (red) to approximately 400 nanometers (violet), although the term optical sometimes includes near infrared and near ultraviolet radiation.
- That which assists vision or the utilization of light. For instance, an optical instrument.