Every meal in ancient Greece began with pouring wine on the ground for the gods — so when someone jokingly calls drinks "libations," they are preserving a 3,000-year-old ritual tradition.
The pouring of a liquid offering to a deity; the liquid poured as an offering; humorously, an alcoholic drink.
From Latin lībātiōnem (accusative of lībātiō, a drink-offering, a libation), from lībāre (to pour out as an offering, to taste, to sip), possibly from Greek leibein (λείβειν, to pour, to make a libation), from PIE *leyb- (to pour, to drip). Key roots: *leyb- (Proto-Indo-European: "to pour, to drip").
Libation was the most common religious act in the ancient world — virtually every meal in Greece and Rome began with pouring a small amount of wine onto the ground for the gods. The practice was so universal that refusing to pour a libation was considered a mark of atheism. The humorous modern usage of "libations" to mean "alcoholic drinks