The word thunderhead 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 thunderhead
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Seven Letter Word Alert: (32 words)
adhered, daunted, denture, denuder, detrend, detrude, detuned, detuner, earthed, earthen, endured, haunted, haunter, hearted, hearten, heathen, heather, hundred, natured, redated, redhead, retuned, tenured, thunder, treaded, trended, undated, unearth, unhated, unheard, unrated, untread