The word matriarchies 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: 20
Highest Scoring Words With Friends™ Play In The Letters matriarchies
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Seven Letter Word Alert: (63 words)
acaters, achiest, airiest, airtime, aitches, amritas, archers, armrest, artsier, atheism, atresia, cameras, carries, carters, cashier, catarrh, charier, charmer, charter, chaster, chemist, chimera, cithers, crasher, craters, cristae, erratic, hairier, hamster, hastier, hermits, irisate, itchier, marcher, marches, marries, matcher, matches, metrics, miscite, mishear, mistier, raciest, ratrace, rechart, reharms, rematch, retrims, richest, satiric, scarier, siriema, smarter, smartie, tarmacs, tarries, thermic, tracers, trachea, tramcar, trasher, triarch, trimers