The word perennation 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™ Plays In The Letters
Seven Letter Word Alert: (28 words)
arenite, entrain, etaerio, inepter, intoner, neonate, nitrene, operant, operate, otarine, painter, peatier, pennant, pentane, pertain, pinnate, pioneer, pointer, pontine, prenote, pronate, protean, protein, repaint, repoint, terpine, trainee, triaene