The word diencephalon 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: 24
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (50 words)
adenine, annelid, cannoli, chained, channel, cheaped, cheapen, chinned, choline, cleaned, codeine, decalin, decline, deplane, dolphin, echelon, echidna, edaphic, eloined, enchain, enhance, epochal, haploid, headpin, helipad, hennaed, inhaled, inplace, leached, nonacid, nondeep, nonepic, nonlead, nonleap, nonpaid, opaline, paneled, panicle, pedicel, pedicle, pelican, penance, pinched, pinhead, pinhold, pinhole, placode, planned, poached, policed