The word troposphere 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™ Plays In The Letters troposphere
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Seven Letter Word Alert: (33 words)
heptose, heteros, hoppers, opposer, poopers, poorest, porters, pothers, presort, prophet, propose, prosper, reports, reposer, reroots, reshoot, reshore, restore, rhetors, rooster, rooters, shooter, shopper, shorter, soother, stepper, stooper, stopper, strophe, toppers, toprope, torpors, trooper