The word cumulonimbuses is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 31
Highest Scoring Words With Friends™ Play In The Letters cumulonimbuses
:
Seven Letter Word Alert: (63 words)
binocle, blouses, boluses, bonuses, bounces, bucines, celsius, cesiums, cession, cobless, columns, combine, commune, consuls, consume, cosines, cosmism, counsel, cousins, cubisms, cubless, cumulus, ebonics, elusion, embolic, embolus, emulous, emulsic, emulsin, ensouls, incomes, incubus, insoles, lesions, leucism, lioness, minuses, miscues, mobiles, moulins, mueslis, mumbles, muonium, muscles, muscone, museums, muslins, nucleus, omnibus, osculum, osmiums, ossicle, sinuous, sluices, sublime, submenu, subsoil, summons, umbones, unbless, unclose, uncoils, unilobe