Word Study
thunderhead
CIDE DICTIONARY
thunderhead, n.
A rounded mass of cloud, with shining white edges; a cumulus, -- often appearing before a thunderstorm. [1913 Webster]
OXFORD DICTIONARY
thunderhead, n. esp. US a rounded cumulus cloud projecting upwards and heralding thunder.
ROGET THESAURUS
thunderhead
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.For further exploring for "thunderhead" in Webster Dictionary Online