The word underivative 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: 23
Highest Scoring Words With Friends™ Plays In The Letters underivative
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Seven Letter Word Alert: (49 words)
arenite, auditee, averted, denarii, denture, detinue, detrain, detuner, deviant, deviate, dietine, diviner, drivein, erudite, evident, inditer, inertia, intrude, invader, invited, invitee, inviter, natured, nitride, reaudit, retuned, reunite, revived, riveted, tenured, tradein, trained, trainee, triaene, unaired, unrated, unrivet, untired, untread, untried, uridine, urinate, uterine, vaunted, veinier, venture, veteran, vitrine, vivider