The word dessiatines 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: 13
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (34 words)
aniseed, assents, daisies, deities, densest, desists, destain, destine, detains, dieties, dietine, disease, dissent, easiest, indites, insides, insists, instead, sadists, sadness, sainted, sateens, seaside, sedates, seitans, seitens, senates, sensate, sestina, sestine, siestas, snidest, stained, standee