Definition of Astigmatic 1. Of or relating to a defect in the eye or in a lens caused by a deviation from spherical curvature which prevents light rays from meeting at a common focus and so results in distorted images Adjective Antonyms to adjective "astigmatic" Lexical Analysis for "astigmatic" anastigmatic not astigmatic astigmatism (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people astigmia (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people