The word dismounted 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: 17
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (29 words)
demount, desmoid, dimuons, distend, dunites, dustmen, endmost, middens, mindset, minuets, minutes, misdone, mistune, moisten, mounded, mounted, mountie, muddies, munited, munites, outside, snouted, sounded, studied, tedious, tediums, toddies, undosed, untimed