The word infestations 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: 17
Highest Scoring Words With Friends™ Plays In The Letters infestations
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Seven Letter Word Alert: (41 words)
anoints, asinine, enfants, fastens, fastest, fatness, fattens, fatties, fiestas, fission, fitness, infants, infests, inosine, inosite, instant, instate, intents, intones, ionises, nations, nonfast, noseans, nosiest, notists, seitans, sestina, setfast, siennas, softens, softest, softies, sonnets, statins, station, stetson, tannest, taoists, tenants, tension, tiniest