| Nebula | n.; pl. Nebulae [ L., mist, cloud; akin to Gr. nefe`lh, ne`fos, cloud, mist, G. nebel mist, OHG. nebul, D. nevel, Skr. nabhas cloud, mist. Cf. Nebule. ] 1. (Astron.) A faint, cloudlike, self-luminous mass of matter situated beyond the solar system among the stars. The term was originally applied to any diffuse luminous region. Now, technically, it is applied to interstellar clouds of dust and gases (diffuse nebula). However distant galaxies and very distant star clusters often appear like them in the telescope, such as the spiral nebula in Andromeda, known now to be a distant galaxy. [ 1913 Webster +PJC ] 2. (Med.) (a) A white spot or a slight opacity of the cornea. (b) A cloudy appearance in the urine. [ Obs. ] [ 1913 Webster ] |
| Nebular | a. Of or pertaining to nebulae; of the nature of, or resembling, a nebula. [ 1913 Webster ]
Nebular hypothesis, an hypothesis to explain the process of formation of the stars and planets, presented in various forms by Kant, Herschel, Laplace, and others. As formed by Laplace, it supposed the matter of the solar system to have existed originally in the form of a vast, diffused, revolving nebula, which, gradually cooling and contracting, threw off, in obedience to mechanical and physical laws, succesive rings of matter, from which subsequently, by the same laws, were produced the several planets, satellites, and other bodies of the system. The phrase may indicate any hypothesis according to which the stars or the bodies of the solar system have been evolved from a widely diffused nebulous form of matter. [ 1913 Webster ]
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