i Register
In some senses, orgiast is marked as idiomatic. Watch for register when choosing this word.
noun
One who attends an orgy.
The cult of Cybele, which for the first time formally organized as a mystic society in Rome, but the orgiast frenzy clung to it at all times.
Rasputin became instrumental in the naming of ministers, men whose qualifications were that they were not going to interfere with the cushy double life he led — as sainted adviser to the royal family and as accomplished orgiast.
One who is prone to excessive indulgence.