astigmatism meaning: definition, etymology

astigmatism

noun

US /əˈstɪɡmətɪzm̩/

Etymology From a- (negative prefix) + stem of Ancient Greek στίγμα (stígma, “mark, point”) + -ism. Coined by English polymath William Whewell in 1846.

Engineering, Natural sciences, Optics, Physical sciences, Physics A defect of a lens such that light rays coming from a point do not meet at a focal point so that the image is blurred.

Medicine, Pathology, Sciences A disorder of the vision, usually due to a misshapen cornea, such that light does not focus correctly on the retina causing a blurred image.

Synonyms: astigmia
Derived terms: anisoastigmatism, astigmatic, astigmatically, mixed astigmatism
Related terms: stigma, stigmatize, emmetropia, hyperopia, myopia, pointlessness