[ uh-stig-muh-tiz-uhm ]

  1. Also called a·stig·mi·a [uh-stig-mee-uh]. /əˈstɪg mi ə/. Ophthalmology. a refractive error of the eye in which parallel rays of light from an external source do not converge on a single focal point on the retina.

  2. Optics. an aberration of a lens or other optical system in which the image of a point is spread out along the axis of the system.

Compare Meanings

Click for a side-by-side comparison of meanings. Use the word comparison feature to learn the differences between similar and commonly confused words.

Origin of astigmatism

First recorded in 1840–50; astigmat(ic) + -ism

Words Nearby astigmatism Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use astigmatism in a sentence

  • If the lines appear with unequal distinctness, some irregularity of refraction (astigmatism) is indicated.

    Physics | Willis Eugene Tower

British Dictionary definitions for astigmatism


astigmia (əˈstɪɡmɪə)

/ (əˈstɪɡməˌtɪzəm) /

  1. a defect of a lens resulting in the formation of distorted images; caused by the curvature of the lens being different in different planes

  2. faulty vision resulting from defective curvature of the cornea or lens of the eye

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for astigmatism


[ ə-stĭgmə-tĭz′əm ]

  1. A visual defect in which the unequal curvature of one or more refractive surfaces of the eye, usually the cornea, prevents light rays from focusing clearly at a single point on the retina, resulting in blurred vision.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for astigmatism


[ (uh-stig-muh-tiz-uhm) ]

A condition in which the curvature of the cornea of the eye is uneven, causing a blurring of vision. Astigmatism is normally corrected by glasses.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.