# astigmatism

> English word · Noun · IPA /əˈstɪɡmətɪzm̩/ · frequency rank #55,927

## Definitions
1. 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.
2. 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.

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

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/astigmatism