The word systematiser 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: 17
Highest Scoring Words With Friends™ Plays In The Letters systematiser
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Seven Letter Word Alert: (75 words)
aeriest, artiest, artists, asserts, attires, easiest, emirate, emitter, essayer, estates, iratest, itemset, iterate, masters, mastery, matters, meatier, messier, metrise, metrist, missays, misseat, misters, reemits, remates, reseats, resists, restate, restems, retaste, reteams, retests, retimes, sassier, satiety, satires, seamers, seamier, seaters, seriate, seriema, sesames, sestets, setters, siamese, siestas, sisters, sitters, smartie, smatter, smiters, staters, statism, stayers, steamer, straits, streams, streamy, streets, striate, stymies, systems, tasters, tastier, teasers, teatime, termite, tersest, testers, testier, tresses, tsarism, tsarist, tsetses, yttrias