The word mouldering 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: 19
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (35 words)
demoing, dilogun, drumlin, dueling, elogium, eluding, eroding, gloried, godlier, gremlin, groined, guerdon, guilder, ignored, indulge, legumin, lounged, lounger, melding, mendigo, mingled, mingler, moldier, molding, mongrel, moulder, mourned, negroid, redoing, regulon, remould, remound, roundel, undergo, unoiled