ASTIGMATISM

astigmatism, astigmia

(noun) (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point

astigmatism, astigmia

(noun) (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people

Source: WordNet® 3.1

Etymology

Noun

astigmatism (countable and uncountable, plural astigmatisms)

(optics) 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.

(pathology) 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

Source: Wiktionary

A*stig"ma*tism, n. Etym: [Gr. astigmatisme.] (Med. & Opt.)

Definition: A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus causing imperfect images or indistictness of vision.

Note: The term is applied especially to the defect causing images of lines having a certain direction to be indistinct, or imperfectly seen, while those of lines transverse to the former are distinct, or clearly seen.

Source: Webster’s Unabridged Dictionary 1913 Edition