The word prankishness 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 prankishness
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Seven Letter Word Alert: (57 words)
arshine, arshins, asepsis, aspires, hankers, hankies, harkens, harness, harpies, heparin, hernias, hipness, hissers, insaner, kaisers, kashers, kinases, kissers, napkins, pansies, paresis, passers, phrases, pinkens, pinkers, praises, raspish, reships, resnaps, respans, respins, sassier, seraphs, shakers, shakier, shapers, sharpen, sharpie, sherpas, shiners, shrieks, shrikes, shrines, shrinks, siennas, sinkers, sinners, skinner, snakier, snakish, snipers, spanker, spanner, spikers, spinner, spireas, sprains