The word rectilinear 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: 16
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (52 words)
airline, alerter, arenite, article, caterer, central, certain, ciliate, citrine, cleaner, clearer, earlier, enteral, enteric, enticer, erratic, eternal, inciter, inerter, inertia, latrine, learner, lectern, lineate, lintier, rainier, ratline, realter, recital, reciter, reclean, recline, recrate, reenact, reinter, relater, relearn, reliant, retinal, retrace, retrain, retrial, tearier, terrace, terrain, terrane, trailer, trainee, trainer, treacle, trenail, triaene