The word diagnostician 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: 21
Highest Scoring Words With Friends™ Play In The Letters diagnostician
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Seven Letter Word Alert: (47 words)
actions, against, agatoid, agnosia, agnosic, agonist, anginas, angioid, anionic, anoints, antacid, atonias, atonics, atoning, canting, cantons, casting, cations, coating, codings, coining, condign, conidia, consign, contain, costing, dancing, diction, dinting, discant, gnostic, goannas, iconist, idiotic, incants, indians, indicts, indigos, nations, niacins, nicosia, nonacid, sanding, satanic, stannic, stoning, tidings