The word perpetuities 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: 19
Highest Scoring Words With Friends™ Play In The Letters perpetuities
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Seven Letter Word Alert: (27 words)
eeriest, peepers, peptise, petites, pettier, pieties, pietist, pipette, pitiers, pretest, putters, puttier, putties, repipes, respite, seepier, sputter, steeper, stepper, stipite, teeters, testier, tippers, tippier, tipsier, tipster, trustee