Why is the ninth month called September?
1550s, from Latin mons Vaticanus, Roman hill on which Papal palace stands. An Etruscan loan-word, not related to vates "sooth-sayer."
The popular name for the Second Vatican Council, an assembly of all the bishops of the Roman Catholic Church held from 1962 to 1965. The bishops ordered a large-scale liberalization and modernization of practices in their church.