The word tendonitis 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: 13
Highest Scoring Words With Friends™ Play In The Letters tendonitis
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Seven Letter Word Alert: (25 words)
dentins, dentist, dietist, ditties, dittoes, dotiest, edition, indents, indites, inosine, inosite, intends, intents, intoned, intones, iodines, iodites, ionised, nondiet, snotted, stinted, tendons, tension, tidiest, tiniest