The word battleship 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 battleship
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Seven Letter Word Alert: (22 words)
albites, aplites, astilbe, atheist, baptise, baptist, batlets, battles, biphase, halites, haplite, latites, libates, patties, petabit, pettish, phablet, pilates, spittle, stealth, tablets, thistle