The word rainforests 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: 15
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (81 words)
antsier, arrests, artsier, atoners, errants, fainter, fairest, fastens, fatness, fiestas, fireant, fitness, foister, forests, forints, forties, fosters, fraters, froster, infests, inserts, insofar, instars, ironers, nastier, norites, nosiest, orients, ornater, otarine, rafters, raisers, ranters, rasters, rations, reasons, refrain, reroast, resifts, resorts, restain, restirs, retains, retinas, retrain, rinsers, rioters, roaster, roister, rosiest, rosters, satires, seitans, senator, seniors, sestina, sierras, sifters, sinters, snarers, snifter, snorers, snorter, soarers, softens, softies, sorters, sorties, stainer, starers, stoners, stonier, stories, strains, strifes, tarries, tensors, terrain, trainer, treason, triones