The word prudishness 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 prudishness
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Seven Letter Word Alert: (33 words)
dressup, hinders, hipness, hissers, hussies, insured, insures, issuers, prudish, purines, pushers, pushier, pussier, pussies, reships, respins, shiners, shrined, shrines, sinuses, snipers, spiders, spurned, sudsers, sudsier, sunrise, suspend, suspire, undress, unipeds, uprisen, uprises, upsides