n. pl. neb·u·lae (-lē′) or neb·u·las
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.
a. A cloudy spot on the cornea.
b. A liquid preparation for use in a nebulizer.
[Middle English nebule, cloud, mist, from Latin nebula; see nebh- in the Appendix of Indo-European roots.]
(click for a larger image)nebula
the Crab Nebula, photographed by the Hubble Space Telescope in 2005
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