The word liverwursts 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™ Plays In The Letters liverwursts
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Seven Letter Word Alert: (29 words)
lusters, lustier, relists, restirs, results, revuist, rivulet, rustier, rustler, rustles, rutiles, silvers, slivers, stivers, striver, strives, suiters, surlier, surveil, sutlers, swirler, swivels, twirler, verists, virtues, viruses, witless, writers, wussier