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