The word rediffusion 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 rediffusion
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Seven Letter Word Alert: (39 words)
differs, diffuse, finders, fondues, founder, friends, funders, indorse, infused, infuser, infusor, insider, insured, iodines, iodiser, ionised, ioniser, ironies, noisier, offends, offside, refinds, refound, refunds, resound, rosined, runoffs, sendoff, sniffed, sniffer, snuffed, snuffer, sounder, undoers, unfired, unified, unifier, unifies, uridine