[ pahr-foh-kuh l ]
/ pɑrˈfoʊ kəl /

adjective Optics.

of or relating to different eyepieces (of telescopes or microscopes) that all focus their images in the same plane, so that they can be interchanged without readjusting the instrument.

Origin of parfocal

First recorded in 1885–90; par1 + focal Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019