astigmatism

Từ điển WordNet v3.1 - WordNet Dictionary

noun

1. (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea;
common in nearsighted people
• Syn:
astigmia
• Derivationally related forms:
astigmatic (for: astigmia), astigmatic
• Topics:
ophthalmology
• Hypernyms:
ametropia
• Hyponyms:
keratectasia, keratoconus
2. (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
• Syn:
astigmia
• Ant:
stigmatism
• Derivationally related forms:
astigmatic (for: astigmia), astigmatic
• Topics:
optics
• Hypernyms:
condition, status