The word determinist 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: 16
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (73 words)
deities, dements, demerit, deniers, dentist, destine, detents, diester, dieters, dieties, dietine, dietist, dimeter, dirties, ditsier, ditties, emitted, emitter, entries, inditer, indites, insider, interim, itemise, itemset, menders, merited, metrise, metrist, minders, mindset, minters, mintier, misedit, mistier, mitered, mitiest, mittens, netters, nitride, nitrite, nittier, reedits, reemits, remends, reminds, remined, remines, remints, retimed, retimes, retints, smitten, stented, sterned, stimied, stinted, tenders, tenters, tentier, termini, termite, testier, tidiers, tidiest, timider, tinders, tiniest, tinters, tintier, tridems, trident, trienes