The word denitrifying 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: 22
Highest Scoring Words With Friends™ Play In The Letters denitrifying
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Seven Letter Word Alert: (30 words)
defying, denting, denying, dieting, dignify, dignity, dingier, dinting, editing, fending, fidgety, finding, fringed, grinned, ignited, igniter, inditer, niftier, nitride, nitrify, reining, rending, renting, retying, rifting, tending, tidying, tiering, tindery, tinnier