An orgy (όργιον) was a secret cultic congregation at nighttime in Ancient Greek religion, overseen by an orgiophant (a teacher or revealer of secret rites).[1] In modern parlance an orgy may refer to an event involving group sex.
Greek όργιον is cognate with έργον "work, effect, [religious] service" (ultimately cognate to English work itself). The term was lent into English in the 16th century, via the Latinized orgia.
Since the 17th century, due to its connection with Dionysus and the Bacchanalia, the English term orgy could refer to "any licentious revelry", in particular group sex or promiscuity, but the term can also denote other acts which may not include sex. For example an "alcoholic orgy" is an event where people show no restraint in alcohol consumption. This is better known as binge drinking.