Also called astigmia
[uh-stig-mee-uh] /əˈstɪg mi ə/ (Show IPA). 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.
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.
a defect of a lens resulting in the formation of distorted images; caused by the curvature of the lens being different in different planes
faulty vision resulting from defective curvature of the cornea or lens of the eye
1849, coined by the Rev. William Whewell (1794-1866), English polymath, from Greek a- “without” (see a- (3)) + stigmatos genitive of stigma “a mark, spot, puncture” (see stick (v.)).
astigmia a·stig·mi·a (ə-stĭg’mē-ə)
astigmatism a·stig·ma·tism (ə-stĭg’mə-tĭz’əm)
A condition in which unequal curvatures along the different meridians in one or more of the refractive surfaces of the eye cause the rays from a light source not to be focused at a single point on the retina. Also called astigmia.
as’tig·mat’ic (ās’tĭg-māt’ĭk) adj. & n.
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.
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.
any plant of the genus Astilbe, of the saxifrage family, having spirelike clusters of small white, pink, or reddish flowers. noun any perennial saxifragaceous plant of the genus Astilbe of E Asia and North America: cultivated for their ornamental spikes or panicles of pink or white flowers
moving or , especially with much activity or excitement: The field was astir with small animals, birds, and insects. up and about; out of bed. Historical Examples But, then, it was so early that not many even of the early-rising farmers were astir. Ruth Fielding In the Red Cross Alice B. Emerson The child was […]
American Society for Testing Materials. abbreviation American Society for Testing and Materials American Society for Testing and Materials