The word peninsulas 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™ Play In The Letters peninsulas
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Seven Letter Word Alert: (23 words)
alpines, inulase, lineups, lipases, lupines, napless, palsies, pansies, pinless, pinnule, punless, salines, sensual, siennas, silanes, spaniel, spinals, spinels, spinule, splines, sunnies, unseals, unsnaps