The word metastasising 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: 19
Highest Scoring Words With Friends™ Plays In The Letters metastasising
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Seven Letter Word Alert: (68 words)
against, agatine, agatise, agitate, amasses, amentia, amnesia, animate, animist, assents, assigns, attains, enigmas, gamiest, gateman, ignites, imagine, imitate, ingests, inmates, inseams, insists, instate, magenta, magnate, magnets, manages, massage, massing, matings, matting, messing, miniate, mintage, misseat, missing, misting, mitiest, mittens, nametag, sagiest, sassing, satiate, seaming, seating, seitans, sestina, setting, siestas, sigmate, signets, simians, sitting, smiting, smitten, stamens, stamina, stating, statins, statism, stigmas, stimies, tasting, teaming, teasing, testing, timings, tiniest