The word blabbermouth is playable in Words With Friends™, but 1 blank substituting for the letter 'b' 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: 24
Highest Scoring Words With Friends™ Plays In The Letters blabbermouth
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Seven Letter Word Alert: (31 words)
armhole, babbler, barbule, belabor, blabber, blather, bloater, blobber, blubber, bomblet, brabble, bramble, bromate, brothel, brumate, bubbler, bumbler, hobbler, humbler, humeral, humoral, loather, mutable, rathole, rubeola, taboule, temurah, thermal, thumber, trouble, tumbler