Nebula (noun)

A cloud of gas and dust in space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.

Origin:

From latin nebula ("mist, cloud"), from nebulus ("cloudy"), from proto-indo-european *nebh- ("cloud, mist").

Examples:

1. The Orion Nebula is one of the most famous nebulae.
2. The Crab Nebula is a supernova remnant.
3. The Horsehead Nebula is a dark nebula.
4. The Rosette Nebula is a bright nebula.
5. The Cat's Eye Nebula is a planetary nebula.