The word lithosphere 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 lithosphere
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Seven Letter Word Alert: (46 words)
elopers, epistle, erotise, estriol, helpers, heptose, heroise, heteros, holiest, holster, hoplite, hostile, hostler, loiters, pelites, pelters, perlite, petiole, petrels, petrols, philter, philtre, phisher, poetise, politer, pothers, repiles, repilot, replies, replots, reptile, respelt, respite, resplit, retiles, ropiest, rosehip, roselet, shelter, slither, spoiler, sterile, strophe, toilers, triples, tripole