The word subdominant 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: 21
Highest Scoring Words With Friends™ Plays In The Letters subdominant
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Seven Letter Word Alert: (33 words)
abounds, amnions, amounts, anoints, astound, bandito, bandits, bastion, batoids, bondman, bunions, diatoms, dimuons, domains, dustbin, dustman, inbound, mansion, mastoid, nations, nonsuit, obtains, omnibus, outbids, outmans, stadium, stannum, submaid, tsunami, unbaits, unbands, unbinds, unstain