The word headmaster 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: 16
Highest Scoring Words With Friends™ Play In The Letters headmaster
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Seven Letter Word Alert: (34 words)
adheres, aerated, aerates, ashamed, dearest, dearths, demates, dharmas, earthed, hamster, hardest, hatreds, headers, headset, hearsed, hearted, heaters, hetaera, readmes, reasted, redates, reheats, remated, remates, reteams, sedater, sheared, smarted, smeared, steamed, steamer, tasered, threads, trashed