The word starchiest 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: 15
Highest Scoring Words With Friends™ Play In The Letters starchiest
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Seven Letter Word Alert: (54 words)
achiest, actress, aitches, artiest, artists, ascites, ashiest, atheist, attires, cashers, cashier, casters, cattier, chaises, chasers, chaster, chatter, cithers, citrate, crashes, cristae, hastier, hatters, hitters, iratest, raciest, racists, rashest, ratchet, rattish, recasts, richest, sachets, satires, scathes, scatter, shatter, sitters, staters, statice, statics, straits, stretch, striate, tartish, tasters, tastier, theists, thirsts, threats, tithers, trashes, trisect, tsarist