astigmatism

astig·ma·tism

noun \ə-ˈstig-mə-ˌtiz-əm\

Definition of ASTIGMATISM

1

: a defect of an optical system (as a lens) causing rays from a point to fail to meet in a focal point resulting in a blurred and imperfect image

2

: a defect of vision due to astigmatism of the refractive system of the eye and especially to corneal irregularity—compare emmetropia, myopia