The word interdependent 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: 22
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (27 words)
deepend, dentine, detente, detrend, entente, entered, inepter, needier, nitrene, pendent, pentene, petered, pettier, preedit, preened, preteen, pretend, printed, repined, ripened, teenier, tentier, tepider, terpene, terpine, trended, trident