HAPAXES is a playable word

hapax Scrabble® Dictionary

noun
pl. hapaxes
a word that occurs only once
67 Playable Words can be made from "HAPAXES"
   2-Letter Words (13 found)
   3-Letter Words (28 found)
   4-Letter Words (18 found)
   5-Letter Words (7 found)
   7-Letter Words (1 found)