The word disinterest 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: 13
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (66 words)
deities, deniers, densest, dentist, deserts, desires, dessert, destine, detents, detests, diester, dieters, dieties, dietine, dietist, dirties, dissent, ditsier, ditties, entries, inditer, indites, inserts, insider, insides, nesters, netters, nitride, nitrite, nittier, redness, reedits, renests, resends, resents, resides, retests, retints, seitens, senders, sestine, setters, sinters, sitters, snidest, stented, sterned, stinted, streets, strides, tenders, tensest, tenters, tentier, tersest, testers, testier, tidiers, tidiest, tinders, tiniest, tinters, tintier, tressed, trident, trienes