The word greaseproof 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: 19
Highest Scoring Words With Friends™ Play In The Letters greaseproof
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Seven Letter Word Alert: (28 words)
apogees, forager, forages, forgers, forgoer, forgoes, grasper, greaser, gropers, poofers, prefers, presage, proofer, reapers, rearose, reforge, regears, regrasp, repages, reparse, reposer, reproof, rerapes, reroofs, roofers, seagoer, spearer, spoofer