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1. slight corneal opacity.
2. an oily preparation for use in a nebulizer.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

neb·u·la (nebul.),

, pl.


(neb'yū-lă, -lē),
1. A translucent foglike opacity of the cornea.
2. A class of oily preparations, intended for application by atomization.
3. A spray.
[L. fog, cloud, mist]
Farlex Partner Medical Dictionary © Farlex 2012


n. pl. nebu·lae (-lē′) or nebu·las
1. Astronomy
a. A diffuse cloud of interstellar dust or gas or both, visible as luminous patches or areas of darkness depending on the way the mass absorbs or reflects incident light or emits its own light.
b. A galaxy. No longer in technical use.
2. Medicine
a. A cloudy spot on the cornea.
b. A liquid preparation for use in a nebulizer.

neb′u·lar adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


, pl. nebulae (neb'yū-lă, -lē)
1. A translucent foglike opacity of the cornea.
2. A spray.
[L. fog, cloud, mist]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A cloudy spot on the CORNEA of the eye. A central nebula can severely interfere with clear vision.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


Dense, white, corneal opacity caused by scar tissue. A localized leukoma appears as a whitish scar surrounded by normal cornea. A generalized leukoma involves the entire cornea, which appears white, often with blood vessels coursing over its surface. Visual impairment depends on the location and extent of the leukoma. If the opacity is faint, it is called a nebula. Note: also spelt leucoma. See hyperacuity; corneal ulcer.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
"The data said you could get bright planetary nebulae from low mass stars like the sun, the models said that was not possible, anything less than about twice the mass of the sun would give a planetary nebula too faint to see."
We now know that planetary nebulae are actually the final stage of activity of stars like our Sun.
What remains at their centers are white dwarf stars, which emit intense ultraviolet radiation that causes the gas in the nebulae to glow and emit light in brilliant colors.
The stars associated with variable nebulae are often situated just inside the edge of a dense molecular cloud through which one of the outflows has punched a conical cavity.
While not particularly useful for star clusters and galaxies, these filters really help bring out planetary nebulae. They block most of the colors of the spectrum except the prominent green light emitted by glowing oxygen atoms.
The Seventh Glow forms a compact equilateral triangle with two famous Messier nebulae that require optical aid to see properly.
When William Herschel discovered it in 1793, he catalogued it as number 73 in his class IV objects: planetary nebulae. Herschel's classification system was morphological, and planetary nebulae to him were anything that appeared small, round and sometimes greenish in colour, i.e.
Sagittarius Nebulae (above) Celestial delights near the direction of the galactic center.
Instead, they represent huge knots of gas that formed when spherical shells of material, known as planetary nebulae, were ejected from the surface of a dying, sunlike star.
Containing only three stars brighter than 3rd magnitude and having no Messier objects within its borders, Aquila may be unfamiliar to some observers, but not to admirers of planetary nebulae. Very few constellations contain as rich and diverse a population of these intriguing and colorful objects as the Eagle.
Planetary nebulae are glowing shells of gas around white dwarfs-Sun-like stars in the final stages of their lives.