neb·u·la (nĕb'yə-lə)
n., pl., -lae (-lē'), or -las.

1. Astronomy.
   1. A diffuse mass 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 radiation.
   2. See galaxy (sense ).
2. Pathology.
   1. A cloudy spot on the cornea.
   2. Cloudiness in the urine.
3. A liquid medication applied by spraying.

[Middle English nebule, cloud, mist, from Latin nebula.]

nebular neb'u·lar adj.

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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

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