The word antepenults 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: 18
Highest Scoring Words With Friends™ Play In The Letters antepenults
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Seven Letter Word Alert: (39 words)
alpeens, annulet, attunes, auletes, eluants, eluates, eluents, epaulet, estuate, eupneas, lateens, latents, leanest, lunates, neatens, neatest, nettles, nutlets, palette, patents, peanuts, peltate, pentane, penults, planets, pulsate, septate, spelean, talents, tannest, tautens, telnets, tenants, tetanus, tunnels, uneaten, unspent, upslant, upstate