The word endoskeletons 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: 21
Highest Scoring Words With Friends™ Play In The Letters endoskeletons
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Seven Letter Word Alert: (34 words)
deletes, denotes, densest, dotless, endless, endnote, keenest, kennels, ketones, ketoses, kneeled, loosens, loosest, needles, nektons, nestled, nestles, netless, noodles, nosodes, oldness, oneness, osselet, osteons, sleeted, snooted, sonnets, soonest, steeled, stenose, stooled, tendons, toeless, tokened