The word luminesced 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 luminesced
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Seven Letter Word Alert: (20 words)
cumenes, deciles, decline, delimes, deslime, emulsic, emulsin, endemic, include, induces, leucine, leucism, license, linseed, miscued, muscled, nuclide, seclude, silence, sluiced