The word crepuscular 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: 23
Highest Scoring Words With Friends™ Play In The Letters crepuscular
:
Seven Letter Word Alert: (32 words)
accruer, accrues, accurse, accuser, alecups, capsule, carpels, carpers, clasper, cupulae, cupular, cupulas, cupules, curlers, parcels, perusal, placers, pursuer, reclasp, recurls, recusal, scalper, scarcer, scraper, scruple, secular, specula, sprucer, surreal, uprears, upscale, usurper