Astronomy .

Also called diffuse nebula. a cloud of interstellar gas and dust. Compare dark nebula , emission nebula , reflection nebula .

(formerly) any celestial object that appears nebulous, hazy, or fuzzy, and extended in a telescope view.

Pathology .

a faint opacity in the cornea.

cloudiness in the urine.

any liquid medication prepared for use as a spray.

noun

galaxy , nimbus , vapor