Source : Webster's Revised Unabridged Dictionary (1913)

Filar \Fi"lar\, a. [L. filum a thread.]
   Of or pertaining to a thread or line; characterized by
   threads stretched across the field of view; as, a filar
   microscope; a filar micrometer.

Source : WordNet®

filar
     adj : related to or having filaments especially across a field of
           view; "afilar eyepiece"