Definition of afocal in English:

afocal

adjective

Optics
  • Of a lens or other optical system: that transfers an image without bringing it to a focus, i.e. so that rays entering parallel emerge parallel; relating to or constituting such a system.

Origin

Late 19th century; earliest use found in Proceedings of the Royal Society of London. From a- + focal.

Pronunciation:

afocal

/eɪˈfəʊkl/