The word fibreglasses 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: 21
Highest Scoring Words With Friends™ Plays In The Letters fibreglasses
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Seven Letter Word Alert: (53 words)
abseils, ageless, airless, bagless, beagles, beliefs, biasses, blesser, blesses, blisses, braises, braless, brasses, earless, faeries, febrile, filabeg, fragile, freesia, friable, frisbee, garbles, gasless, gassers, gassier, gerbils, glasses, grasses, greases, largess, lassies, leafier, leasers, ligases, realise, rebales, rebases, rebless, refiles, reflags, reflies, reliefs, resails, resales, reseals, ribless, sailers, sassier, sealers, sealife, selfies, serials, sessile