The word deferments 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 deferments
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Seven Letter Word Alert: (25 words)
defense, dements, demesne, emender, emersed, entered, entrees, feeders, fenders, ferment, freemen, meeters, menders, metered, needers, redeems, reested, refeeds, remeets, remends, sneered, steered, sterned, teemers, tenders