The word undutifulness 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: 23
Highest Scoring Words With Friends™ Play In The Letters undutifulness
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Seven Letter Word Alert: (53 words)
delints, delists, dentils, dentins, desilts, diluent, dilutes, dissent, duelist, dunites, dutiful, enlists, finless, fistule, fitness, fluents, funnels, funnest, funnies, indents, infests, infused, infuses, insults, intends, lindens, linnets, listens, luniest, nudists, silents, snidest, stifled, stifles, studies, stunned, sulfide, sulfite, sunnies, tinfuls, tinsels, tissued, tuneful, tunnels, tussled, undents, undines, unfused, unlined, unlists, untiled, untuned, utensil