The word lockmaster 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 lockmaster
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Seven Letter Word Alert: (50 words)
alecost, armlets, armlock, calmest, cartels, clamors, clarets, coakers, coalers, coaster, colters, earlock, escolar, lactose, locates, lockers, lockets, lockset, mackles, maestro, maltose, markets, mockers, morales, mortals, octamer, oracles, rackets, recloak, recoals, recoats, relocks, restack, restock, retacks, rockets, scarlet, scrotal, slacker, smacker, solacer, stacker, stalker, stocker, stromal, tackers, tackler, tackles, talkers, tramels