The word sparsities 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: 13
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (34 words)
airiest, asepsis, aspires, asserts, irisate, paresis, parties, passers, pasters, pastier, pasties, persist, piarist, pirates, pissier, pitiers, praises, priests, rapists, repasts, resists, sassier, satires, siestas, sissier, sisters, sparest, spireas, spirits, spriest, sprites, stripes, tipsier, traipse