Vatican City
The name was first used in the Lateran Treaty, signed on 11 February 1929, which established the modern city-state. The name is taken from Vatican Hill, the geographic location of the state. "Vatican" is derived from the name of an Etruscan settlement, "Vatica" or "Vaticum" meaning garden, located in the general area the Romans called "vaticanus ager", "Vatican territory".
Infallibility of the Church
The doctrine of papal infallibility was formally defined at the First Vatican Council in 1870, although belief in this doctrine long predated this council and was premised on the promises of Jesus to Peter, promises to Peter (Mat 16:16-20; Luke 22:32). The encyclicals of the First Vatican Council, however were rejected by a small minority of bishops who separated themselves from union with the Bishop or Rome to form, or preserve, the Old Catholic Church.