Either of two ecumenical councils of the Roman Catholic Church, the First Vatican Council (1869-1870) and the Second Vatican Council (1962-1965), convoked by Pius IX and John XXIII, respectively. The First is noted for its affirmation of papal infallibility, and the Second resulted in the revision of most of the liturgy, the replacement of Latin with vernacular languages in rites, and more open relationships with non-Catholic denominations.