The word dismounting 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 dismounting
:
Seven Letter Word Alert: (26 words)
dimuons, dinting, diosmin, dousing, dusting, gnomist, indigos, indiums, minding, minions, minting, misting, mousing, nonsuit, ousting, outings, sigmoid, smidgin, smiting, stoning, suiting, tidings, timings, tunings, undoing, uniting