The word interestingness 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: 20
Highest Scoring Words With Friends™ Play In The Letters interestingness
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Seven Letter Word Alert: (88 words)
eeriest, engines, ensigns, entente, entrees, entries, geneses, genesis, greisen, igniter, ignites, ingests, ingress, innings, inserts, insists, integer, intense, intents, interns, nesters, nesting, netters, netting, nitrene, nitrite, nittier, regents, reining, reneges, renests, rennets, rennins, renting, resents, resigns, resists, resting, retests, retints, rinsing, risings, seitens, sensing, sestets, sestine, settees, setters, setting, signees, signers, signets, singers, sinners, sinning, sinters, sissier, sisters, sitters, sitting, stinger, streets, strings, teenier, teeters, tenners, tensest, tensing, tenters, tentier, tenting, tersest, testers, testier, testing, tiering, tigress, tiniest, tinners, tinnier, tinning, tinters, tintier, tinting, treeing, tresses, trienes, tsetses