Neb"u*la (?), n.; pl. Nebulae (#). [L., mist, cloud; akin to Gr. , , cloud, mist, G. nebel mist, OHG. nebul, D. nevel, Skr. nabhas cloud, mist. Cf. Nebule.]
A faint, cloudlike, self-luminous mass of matter situated beyond the solar system among the stars. True nebulae are gaseous; but very distant star clusters often appear like them in the telescope.
<-- also applied now to galaxies -->
2. Med. (a)
A white spot or a slight opacity of the cornea.
A cloudy appearance in the urine.
© Webster 1913.