orgy

noun3

1. •
   A gathering of people to engage in group sex.
2. •
   An instance or period of excessive indulgence in a specified activity; spree.

   • As two Homeric warriors, before they engage, introduce themselves by proclaiming each his lineage, so with Pelasgus and the Danaïds. Together they indulge in a veritable genealogical orgy. — 1924
3. •
   A secret rite or ceremony, typically involving riotous and dissolute behavior, including dancing, drunkenness and indiscriminate sexual activity, undertaken in honor of various pagan gods or goddesses (such as Attis, Bacchus, Ceres, Dionysus, Osiris, etc).

   • Human sacrifices of a definitely black magical order took place at the tomb of Osiris, while similar orgies with human victims were performed at Heliopolis. — 1936