A rounded projecting mass of a cumulus cloud with shining edges; often appears before a thunderstorm.

Roget 353: 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.    [Science of clouds] nephelognosy^†; nephograph^†, nephology^†.    effervescence, fermentation; bubbling etc. v.. nebula; cloudliness etc. (opacity) 426^†; nebulosity etc. (dimness) 422.    ... show more