noun \ˈne-byə-lə\

: a cloud of gas or dust in space that can sometimes be seen at night

: a group of stars that are very far away and look like a bright cloud at night

plural neb·u·lae\-ˌlē, -ˌlī\ also neb·u·las

Full Definition of NEBULA

:  any of numerous clouds of gas or dust in interstellar space
:  galaxy 1b; especially :  a galaxy other than the Milky Way galaxy —not used technically
neb·u·lar \-lər\ adjective

Origin of NEBULA

New Latin, from Latin, mist, cloud; akin to Old High German nebul fog, Greek nephelē, nephos cloud
First Known Use: 1718


noun \ˈneb-yə-lə\   (Medical Dictionary)
plural neb·u·las or neb·u·lae \-ˌlē, -ˌlī\

Medical Definition of NEBULA

: a slight cloudy opacity of the cornea


noun    (Concise Encyclopedia)

Any of various tenuous clouds of gas and dust in interstellar space. Nebulae constitute only a small percentage of a galaxy's mass. Dark nebulae (e.g., the Coalsack) are very dense, cold molecular clouds that appear as large, obscure, irregularly shaped areas in the sky. Bright nebulae (e.g., the Crab Nebula, planetary nebula) appear as faintly luminous, glowing surfaces; they emit their own light or reflect that of stars near them. The term nebula also formerly referred to galaxies outside the Milky Way Galaxy.


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