secret rite in the cults of ancient Greek or Roman deities involving singing and dancing and drinking and sexual activity
"The historian argued that the archaeological findings at the temple site were evidence of an ancient orgy dedicated to Dionysus."
a wild gathering involving excessive drinking and promiscuity
"The party quickly descended into an orgy when everyone started bringing bottles of champagne and strangers began dancing on top of each other."
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).
"The ancient historian described the wild orgy held at the spring festival as a secret rite dedicated to Dionysus that involved days of dancing and drunkenness."
In plain English: An orgy is a wild party where a large group of people engage in sexual activities together.
"The party turned into an all-night orgy of dancing and drinking."
Usage: In modern usage, an orgy refers to a gathering where people engage in excessive drinking and indiscriminate sexual activity. Avoid using this word to describe any form of religious ceremony or historical ritual.
The word entered English as a plural noun borrowed directly from the French orgies. It traces its roots to the Ancient Greek term for secret religious rites and mysteries.