The word jackrabbiting 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: 38
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (22 words)
abating, backbar, backbit, backing, baiting, barbing, bargain, barking, bracing, braking, bribing, carting, crating, jabbing, jacking, racking, ribbing, ricking, tabbing, tacking, ticking, tracing