Library / English Dictionary

ASTIGMATISM

Pronunciation (US):

(GB):

 I. (noun) 

Sense 1

Meaning:

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

Synonyms:

astigmatism; astigmia

Classified under:

Nouns denoting stable states of affairs

Hypernyms ("astigmatism" is a kind of...):

condition; status (a state at a particular time)

Domain category:

optics (the branch of physics that studies the physical properties of light)

Antonym:

stigmatism ((optics) condition of an optical system (as a lens) in which light rays from a single point converge in a single focal point)

Derivation:

astigmatic (of or relating to a defect in the eye or in a lens caused by a deviation from spherical curvature which prevents light rays from meeting at a common focus and so results in distorted images)

Sense 2

Meaning:

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

Synonyms:

astigmatism; astigmia

Classified under:

Nouns denoting stable states of affairs

Hypernyms ("astigmatism" is a kind of...):

ametropia ((ophthalmology) faulty refraction of light rays in the eye as in astigmatism or myopia)

Domain category:

ophthalmology (the branch of medicine concerned with the eye and its diseases)

Hyponyms (each of the following is a kind of "astigmatism"):

keratectasia (abnormal bulging of the cornea of the eye)

keratoconus (abnormal cone-shaped protrusion of the cornea of the eye; can be treated by epikeratophakia)

Derivation:

astigmatic (of or relating to a defect in the eye or in a lens caused by a deviation from spherical curvature which prevents light rays from meeting at a common focus and so results in distorted images)

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