The word thickeners 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: 20
Highest Scoring Words With Friends™ Play In The Letters thickeners
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Seven Letter Word Alert: (40 words)
centers, centres, cistern, cithern, cithers, cretins, enteric, enticer, entices, entries, etchers, etheric, ethnics, heretic, inchers, kernite, kitchen, necktie, neither, recites, reknits, reshine, restick, retches, rethink, richest, rickets, scenter, sincere, snicker, sticker, stinker, techies, therein, thicken, thicker, thinker, tickers, tinkers, trienes