The word frostiness 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: 14
Highest Scoring Words With Friends™ Play In The Letters frostiness
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Seven Letter Word Alert: (32 words)
fitness, foister, forests, forints, forties, fosters, infests, inserts, norites, nosiest, orients, osseins, resifts, resists, rosiest, seniors, sensors, session, sifters, sinters, sisters, snifter, softens, softies, sorties, stoners, stonier, stories, strifes, tensors, tossers, triones