noun

1. Originally, secret rites or ceremonies, typically involving riotous and dissolute behaviour, including dancing, drunkenness and indiscriminate sexual activity, undertaken in honour of various pagan gods or goddesses (such as Attis, Bacchus, Ceres, Dionysus, Osiris, etc).

2. A gathering of people to engage in group sex.

3. Excessive indulgence in a specified activity.