The word dissimilitude 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 dissimilitude
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Seven Letter Word Alert: (35 words)
delimit, delists, demists, desilts, desmids, diimide, diluted, dilutes, distils, disused, duelist, elitism, ileitis, limited, luddite, middles, mildest, misedit, missile, missuit, misused, muddies, muddles, mueslis, sidelit, similes, stimied, stimies, stimuli, studied, studies, tediums, tissued, tussled, utilise