The word concomitance is playable in Words With Friends™, but 1 blank substituting for the letter 'c' is 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: 22
Highest Scoring Words With Friends™ Plays In The Letters concomitance
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Seven Letter Word Alert: (21 words)
aconite, ancient, cacemic, canonic, catenin, cocaine, cometic, conceit, concoct, connect, connote, contain, emotion, meconic, mention, montane, nematic, nonmate, nonmeat, oceanic, oncotic