The word creditably 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 creditably
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Seven Letter Word Alert: (40 words)
acridly, article, baldric, bedirty, bedrail, bilayer, bracted, brailed, caliber, calibre, carbide, catbird, citable, citadel, clarity, clayier, decabit, decrial, deltaic, dialect, dietary, dilater, driblet, icetray, irately, libated, liberty, lyrated, rabidly, radicel, radicle, readily, reality, recital, tardily, tearily, tiredly, trailed, treacly, triable