Source : Webster's Revised Unabridged Dictionary (1913)

Anastigmatic \An*as`tig*mat"ic\, a. [Pref. an-not + astigmatic.]
   (Optics)
   Not astigmatic; -- said esp. of a lens system which consists
   of a converging lens and a diverging lens of equal and
   opposite astigmatism but different focal lengths, and
   sensibly free from astigmatism.

Source : WordNet®

anastigmatic
     adj 1: pertaining to a lens or lens system free of astigmatism
            (able to form point images) [syn: {stigmatic}]
     2: not astigmatic [syn: {stigmatic}] [ant: {astigmatic}]