The word streetlights 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: 17
Highest Scoring Words With Friends™ Play In The Letters streetlights
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Seven Letter Word Alert: (48 words)
eighter, elegist, elegits, glister, glitter, gristle, heiress, hessite, hitters, letters, lighter, litters, relight, relists, resight, retests, retiles, retilts, retitle, setters, settler, settles, shelter, sighers, sighter, sitters, sleighs, sleight, slights, slither, slitter, sterile, stilter, streets, tersest, testers, testier, tethers, theists, thirsts, thistle, tieless, tighter, tigress, tilters, tithers, titters, trestle