neb ‧ u ‧ la /ˈnebjələ, ˈnebjʊlə/ BrE AmE noun ( plural nebulae /-liː/) [countable]
[ Date: 1600-1700 ; Language: Latin ; Origin: 'mist, cloud' ]
1 . a mass of gas and dust among the stars, which often appears as a bright cloud in the sky at night
2 . a ↑ galaxy (=mass of stars) which appears as a bright cloud in the sky at night
—nebular adjective