The word geothermally 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: 23
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (31 words)
aerogel, alertly, alleger, allegro, allergy, armhole, eagerly, earthly, gallery, gloater, greatly, hygroma, largely, lathery, leather, loather, loathly, loyaler, morally, rathole, reallot, regally, retally, tallyho, telomer, theorem, thermal, tollage, tramell, trolley, yealmer