The word tramlines 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: 14
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (58 words)
ailment, aliment, antlers, antsier, armlets, artsmen, elastin, entails, inmates, laments, latrine, mailers, maltier, manlier, mantels, mantles, marines, marlins, marlite, martens, martins, minaret, mineral, minters, mistral, nailers, nailset, nastier, netmail, raiment, ratline, realism, realist, reliant, remails, remains, remints, renails, rentals, reslant, restain, retails, retains, retinal, retinas, salient, saltern, saltier, seminal, seminar, sirname, slatier, smarten, smartie, stainer, sternal, tramels, trenail