The word terrapins 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™ Play In The Letters
Seven Letter Word Alert: (39 words)
antsier, artsier, aspirer, entraps, errants, nastier, painter, panters, panties, parents, parties, partner, pastier, patines, pertain, pirates, praiser, praters, pretans, printer, pterins, ranters, raspier, repaint, repairs, reprint, restain, restrap, retains, retinas, retrain, retraps, stainer, striper, tarries, terrain, trainer, traipse, trepans