The word posteriorities 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
Seven Letter Word Alert: (89 words)
erotise, isotope, persist, pesters, petites, pettier, pieties, pietist, pissier, pitiers, poesies, poetess, poetise, poorest, poroses, porosis, porters, posters, potters, potties, presets, presort, presser, pretest, priests, protest, protist, reports, reposer, reposes, reposts, repress, reprise, reroots, resorps, resorts, respire, respite, respots, resteps, resters, restirs, restore, retests, retires, retorts, retries, rioters, risotto, roister, rooster, rooters, ropiest, rosette, rosiest, rosters, rotters, septets, setters, sitters, soirees, sootier, sorters, sorties, spirits, spotter, spriest, sprites, stereos, stipite, stooper, stories, streets, striper, stripes, tersest, testers, testier, tipsier, tipster, tiptoer, tiptoes, tooters, tootsie, torpors, tosspot, treetop, trooper, tropist