The word depopulation 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: 22
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (51 words)
applied, appoint, autopod, diluent, elation, elution, euploid, lunated, nepotal, nippled, notepad, nuptial, opaline, opiated, opulent, outdone, outlead, outleap, outline, outpipe, outplan, outplod, painted, patined, pentail, petunia, piloted, plaited, planted, platoon, plaudit, pleopod, pointed, poundal, poutine, pupated, tadpole, talonid, telopod, tippled, toenail, toluide, topline, toppled, undealt, unideal, unipole, unoiled, untaped, untiled, utopian