Main Entry: op·ti·cal

Pronunciation: \ˈäp-ti-kəl\

Function: adjective

Date: 1570

1 : of or relating to the science of optics
2 a : of or relating to vision : visual b : visible 1 <optical wavelength> c : of, relating to, or being objects that emit light in the visible range of frequencies <an optical galaxy> d : using the properties of light to aid vision <an optical instrument>
3 a : of, relating to, or utilizing light especially instead of other forms of energy <optical microscopy> b : involving the use of light-sensitive devices to acquire information for a computer <optical character recognition>
4 : of or relating to optical art

— op·ti·cal·ly \-k(ə-)lē\ adverb