The word stringently 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: 18
Highest Scoring Words With Friends™ Play In The Letters stringently
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Seven Letter Word Alert: (46 words)
girnels, glisten, glister, glitter, gristle, gristly, inertly, instyle, intents, interns, lensing, letting, lingers, linnets, litters, nesting, netting, nitryls, relying, renting, resting, retilts, retints, retying, ringlet, setting, singlet, slinger, slitter, sternly, stilter, stinger, stringy, stylier, styling, syringe, tensing, tenting, testily, testing, tilters, tingler, tingles, tinners, tinters, triynes