The word jiggermasts 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: 27
Highest Scoring Words With Friends™ Play In The Letters jiggermasts
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Seven Letter Word Alert: (32 words)
aggress, aigrets, gaiters, gamiest, gassier, imagers, jaggier, jiggers, masters, migrate, mirages, misseat, misters, ragtime, ramjets, saggers, saggier, sagiest, satires, sigmate, smartie, smiters, stagers, stagger, stagier, stigmas, streams, taggers, taggier, tigress, triages, tsarism