THESAURUS
Nebula
Black Magellanic Cloud, Crab
Nebula, Gegenschein, bright diffuse nebula, coalsack, counterglow, dark cloud, dark nebula, diffuse nebula, dust cloud, gaseous nebula, nebula of Lyra, nebular hypothesis, nebulosity, nebulous stars, planetary nebula, ring nebula, the Coalsack, zodiacal light
ROGET THESAURUS
Nebula
Bubble
N
bubble; cloud, bubble, foam, froth, head, spume, lather, suds, spray, surf, yeast, barm, spindrift, cloud, vapor, fog, mist, haze, steam, geyser, scud, messenger, rack, nimbus, cumulus, woolpack, cirrus, stratus, cirrostratus, cumulostratus, cirrocumulus, mackerel sky, mare's tale, dirty sky, curl cloud, frost smoke, thunderhead, nephelognosy, nephograph, nephology, effervescence, fermentation, bubbling, nebula, cloudliness, nebulosity, bubbling, frothy, nappy, effervescent, sparkling, mousseux, frothy, up, cloudy, thunderheaded, vaporous, nebulous, overcast, the lowring element scowls o'er the darkened lands.