noun Date: 1846 1. a defect of an optical system (as a lens) causing rays from a point to fail to meet in a focal point resulting in a blurred and imperfect image 2. a defect of vision due to astigmatism of the refractive system of the eye and especially to corneal irregularity 3. distorted understanding suggestive of the blurred vision of an astigmatic person

New Collegiate Dictionary. 2001.

Look at other dictionaries:

  • astigmatism — ASTIGMATÍSM s.n. Aberaţie a unui sistem optic, care formează o imagine întinsă pentru un obiect. ♦ Defect al lentilelor sau al corneei şi cristalinului ochiului omenesc, care constă într o abatere de la forma sferică, ele având razele de curbură… …   Dicționar Român

  • Astigmatism — A*stig ma*tism, n. [Gr. a priv. + ?, ?, a prick of a pointed instrument, a spot, fr. ? to prick: cf. F. astigmatisme.] (Med. & Opt.) A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a… …   The Collaborative International Dictionary of English

  • astigmatism — 1849, coined by the Rev. William Whewell (1794 1866), English polymath, from Gk. a without + stigmatos gen. of stigma a mark, spot, puncture (see STICK (Cf. stick) (v.)) …   Etymology dictionary

  • astigmatism — ► NOUN ▪ a defect of the eye or a lens, resulting in distorted images. DERIVATIVES astigmatic adjective. ORIGIN from Greek stigma point …   English terms dictionary

  • astigmatism — [ə stig′mə tiz΄əm] n. [< Gr a , without + stigma (gen. stigmatos) a mark, puncture (see STICK) + ISM] 1. an irregularity in the curvature of a lens, including the lens of the eye, so that light rays from an object do not meet in a single focal …   English World dictionary

  • Astigmatism — An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp… …   Wikipedia

  • Astigmatism — A common form of visual impairment in which part of an image is blurred, due to an irregularity in the curvature of the front surface of the eye, the cornea. The curve of the cornea is shaped more like an American football or a rugby ball rather… …   Medical dictionary

  • astigmatism — /euh stig meuh tiz euhm/, n. 1. Also called astigmia /euh stig mee euh/. Ophthalm. 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… …   Universalium

  • astigmatism — Ametropia Am e*tro pi*a, n. [Gr. ? irregular + ?, ?, eye.] (Med.) a visual impairment resulting from faulty refraction of light rays in the eye. Subtypes include {myopia} {astigmatism} and {hyperopia}. {Am e*trop ic}, a. [1913 Webster +PJC] …   The Collaborative International Dictionary of English

  • astigmatism — [[t]əstɪ̱gmətɪzəm[/t]] N UNCOUNT If someone has astigmatism, the front of their eye has a slightly irregular shape, so they cannot see properly …   English dictionary

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