The word myelencephalon 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: 31
Highest Scoring Words With Friends™ Play In The Letters myelencephalon
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Seven Letter Word Alert: (37 words)
alchemy, allonym, amylene, anemone, calomel, cayenne, channel, cheapen, cheaply, chyloma, cleanly, coalmen, company, echelon, empanel, emplace, emplane, enhance, eonymph, epochal, eyehole, halcyon, manhole, maypole, nomancy, nonclay, nonleap, nonmale, nonmeal, nonplay, nymphal, pacemen, penance, penname, phoneme, ponyman, ponymen