The word semilunar 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: 15
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (26 words)
arenium, emulsin, insular, inulase, mailers, manlier, manures, marines, marlins, maulers, mensual, mineral, misrule, nailers, numeral, realism, remails, remains, renails, ruminal, seminal, seminar, serumal, sirname, surname, urinals