The word mammothermography cannot be made in Words With Friends™. It is 17 letters long, too long to fit on a WordsWithFriends board (15 letters max).
Highest Scoring Words With Friends™ Play In The Letters mammothermography
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Seven Letter Word Alert: (40 words)
aerator, amorphy, amphora, apogamy, aptamer, atrophy, empathy, grammar, grommet, groomer, gyrator, homomer, hygroma, mammary, mammoth, margate, moorage, myogram, myomata, myotome, oophyte, oratory, pharaoh, portage, portray, praetor, program, promote, prorate, rampage, rampart, regraph, regroom, taproom, tearoom, therapy, thymoma, trammer, tramper, trooper