Source : Webster's Revised Unabridged Dictionary (1913)

Nebula \Neb"u*la\, n.; pl. {Nebul[ae]}. [L., mist, cloud; akin
   to Gr. ?, ?, 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. True
      nebul[ae] are gaseous; but very distant star clusters
      often appear like them in the telescope.

Source : WordNet®

nebula
     n 1: a medicinal liquid preparation intended for use in an
          atomizer
     2: cloudiness of the urine
     3: an immense cloud of gas (mainly hydrogen) and dust in
        interstellar space
     4: (pathology) a faint cloudy spot on the cornea
     [also: {nebulae} (pl)]

Source : Free On-Line Dictionary of Computing

Nebula
     
        An early business-oriented language from {ICL} for the
        {Ferranti Orion} computer.
     
        ["NEBULA - A Programming Language for Data Processing", T.G.
        Braunholtz et al, Computer J 4(3):197-201 (1961)].
     
        (1994-11-29)