The word responsibleness 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: 24
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (81 words)
beeline, beepers, bipoles, bleeper, blesser, blesses, blisses, boilers, bonnier, boreens, bossier, ebonies, elopers, ennoble, enrobes, epsilon, insoles, lesions, lessees, lessens, lessons, lessors, lioness, lispers, lossier, nonslip, oneness, onliner, openers, osseins, peelers, penises, penners, pennies, pension, peonies, persons, pieless, pinenes, pinless, pioneer, pleions, poesies, possess, preboil, presses, prisons, proline, rebless, reboils, relines, reopens, repeels, repiles, repines, replies, reposes, resoils, resoles, respins, ribless, riboses, seepier, seniors, sensors, sessile, session, sinless, sinners, sleeper, slopers, snipers, soirees, sonless, spinels, spinner, spinons, spinose, spleens, splines, spoiler