paroxysmal

paroxysmal is a valid word in Scrabble and Words With Friends. It has 10 letters and scores 24 points before any board bonuses (p 3 + a 1 + r 1 + o 1 + x 8 + y 4 + s 1 + m 3 + a 1 + l 1).

“PAROXYSMAL” on Wiktionary