The word defensibility 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: (55 words)
beetfly, beliefs, bendlet, benefit, bentley, betides, bylined, bylines, defiles, defines, deifies, deities, delints, densely, densify, density, dentils, destine, destiny, dieties, dietine, distyle, dyeline, edibles, edifies, eleidin, enstyle, eyelids, eyelift, eyeslit, feedbin, felines, felsite, fileted, flensed, ileitis, indites, infidel, infield, instyle, lefties, lenited, lenites, linseed, needily, nestled, niftily, seedily, sidelit, snidely, stifled, syenite, tensely, tensile, yeelins