The word interposition 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: 18
Highest Scoring Words With Friends™ Play In The Letters interposition
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Seven Letter Word Alert: (80 words)
erosion, inosine, inosite, inspire, intents, interns, intoner, intones, intorts, introns, ioniser, ionones, ironies, isotope, nitrite, nittier, noisier, nonpros, nonriot, nonstop, norites, notions, operons, opinion, options, orients, pension, pietist, pinions, pitiers, pointer, pontine, poorest, portent, portion, postern, potions, potters, potties, pronest, protein, protest, protist, protons, pterins, repoint, retints, risotto, ropiest, snooper, snotter, sootier, spinier, spinner, spinnet, sporont, spotter, stipite, stonier, stooper, tenpins, tension, tiepins, tiniest, tinners, tinnier, tinpots, tinters, tintier, tipsier, tipster, tiptoer, tiptoes, toonies, tooters, tootsie, tornote, torsion, triones, tropist