The word adversaries 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™ Plays In The Letters adversaries
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Seven Letter Word Alert: (44 words)
adverse, advisee, adviser, advises, arrived, arrives, averred, averser, dearies, deriver, derives, derries, desirer, desires, deviser, devises, disease, diverse, dresser, drivers, erasers, evaders, raiders, raisers, readers, readier, readies, rearise, reavers, redress, redries, redrive, rereads, resaved, resaves, resider, resides, revised, reviser, revises, rivered, seaside, servers, sierras