The word unharnessed 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: 17
Highest Scoring Words With Friends™ Plays In The Letters unharnessed
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Seven Letter Word Alert: (36 words)
adheres, arsheen, assured, asunder, dashers, deashes, endears, endures, ensears, ensnare, ensured, ensures, handers, hardens, harness, headers, hearsed, hearses, hennaed, herdess, redness, resands, resends, sanders, senders, shaders, sheared, shunned, shunner, sundaes, undress, unhands, unheard, unshare, ureases, ushered