In ancient Greece and Rome, lustratio (lustration) was a purification ritual, which included a procession and in some circumstances the sacrifice of a pig, a ram and a bull.
In Rome, a census was taken every five years. King Servius (the legendary sixth king of Rome) is said to have performed a lustration after his first census, in 556 BC, and it is said to have taken place after each census from that time onwards. The word lustrum came to mean the five–year period between two censuses and two lustrations.
© Haydn Thompson 2021