The word parameciums 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: 24
Highest Scoring Words With Friends™ Play In The Letters parameciums
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Seven Letter Word Alert: (28 words)
aupairs, auspice, caesium, cameras, campers, campier, ceriums, icespar, immures, macrame, maimers, premium, primase, pumicer, pumices, samurai, saucier, scamper, spacier, spammer, spermic, spiraea, spumier, umpires, upraise, uraemia, uraemic, uricase