Meaning of dark nebula

dark' neb'ula

Pronunciation: [key]
— Astron. Astron.
  1. a cloud of interstellar gas and dust that absorbs and thus obscures the light from stars behind it, appearing as a dark patch in front of a bright nebula or in an otherwise bright area of sky. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.