" astigmatism "

[Noun]  | "astig*ma*tism" | \ ə-ˈstig-mə-ˌti-zəm \

1: a defect of an optical system (such 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

Origin: 1831 ;

 {see: |a-:2|a-:2} + Greek stigmat-, stígma mathematical point, mark, tattoo mark (more usually stigmḗ in this sense; referring to the point on the retina at which light rays converge in a normal eye) + {see: |-ism|-ism} {mat|stigma|};

  * Note : The term astigmatism was introduced by the British astronomer George Biddell Airy (1801-92), who performed a pioneering measurement and description of an astigmatism in his own eye (On a Peculiar Defect of the Eye and a Mode of Correcting It, Transactions of the Cambridge Philosophical Society, vol. 2 [1827], pp. 267-71). Airy did not use the word in the article, however, and it does not see:m to appear under his name until a much later article on the same subject, On a Change in the State of an Eye affected with a Mal-formation [Read May 25, 1846], Transactions of the Cambridge Philosophical Society, vol. 8 (1849), pp. 361-62. In the latter article Airy describes the nature of the effect as a geometrical phenomenon, to which the term astigmatism was very happily affixed by the present Master of Trinity College. The Master of Trinity College, Cambridge, was the clergyman and polymath William Whewell (1794-1866), to whom a number of other scientific neologisms are credited. The word was evidently in oral circulation prior to Airy's use of it in print; in 1831, an unsigned article in The British Critic, Quarterly Theological Review, and Eccesiastical Record (vol. 9, p. 82) mentions astigmatism, employing a word which we believe Professor Airy is in the habit of using in his lectures on this subject [optics]. For details on Airy and astigmatism, see: John R. Levene, Sir George Biddell Airy, F.R.S. (1801-1892) and the Discovery and Correction of Astigmatism, Notes and Records of the Royal Society of London, Vol. 21, No. 2 (December, 1966), pp. 180-199.;

[Noun]  | "astigmatism"