The word uncheerfulness 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: 27
Highest Scoring Words With Friends™ Play In The Letters uncheerfulness
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Seven Letter Word Alert: (51 words)
censers, censure, cheeses, crushes, ensures, essence, eunuchs, feelers, fencers, fennels, fescues, fleecer, fleeces, flenser, flenses, fleshes, flusher, flushes, freshen, fuelers, funnels, furless, herself, hueless, lechers, leecher, leeches, luncher, lunches, lurches, nucleus, recluse, recuses, refence, reflush, refuels, refuses, reheels, rescues, runnels, screens, secerns, secures, shunner, slusher, sulfurs, uncurls, uncurse, unfurls, unreels, urnfuls