The word decelerates 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: 16
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (59 words)
alerted, altered, cartels, castled, catered, cerates, cereals, clarets, cleared, cradles, creased, created, creates, crested, dealers, dearest, decares, decease, declare, decrees, deerlet, delates, deleter, deletes, descale, elaters, elected, electee, erected, leaders, reacted, realest, reasted, recedes, reclads, redacts, redates, redeals, redealt, reelect, reested, relaced, relaces, related, relates, release, rescale, scarlet, sclerae, seceder, secrete, sedater, sleeted, stealer, steeled, steered, tasered, treacle, treadle