The word defensibilities 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: (74 words)
bedless, bedsits, beeline, beetled, beetles, beliefs, bendlet, benefit, besides, betides, blessed, blissed, defense, defiles, defines, deifies, deities, deletes, delints, delists, densest, dentils, desilts, destine, diesels, dieties, dietine, dissent, distils, edibles, edifies, eleidin, endless, enlists, feedbin, felines, felsite, fileted, finesse, finless, fissile, fitness, fleeted, flensed, flenses, ileitis, indites, infests, infidel, infield, insides, lefties, lenited, lenites, linseed, listens, needles, nestled, nestles, netless, seitens, selfies, sestine, sidelit, silents, sleeted, snidest, steeled, steelie, stifled, stifles, tensile, tieless, tinsels