(from Medieval Latin ultramontanus, “beyond the mountains”), in Roman Catholicism, a strong emphasis on papal authority and on centralization of the church. The word identified those northern European members of the church who regularly looked southward beyond the Alps (that is, to the popes of Rome) for guidance.

During the period of struggle within the church over the extent of papal prerogatives—beginning especially in the 15th century with the conciliar movement and continuing in the following centuries with the growth of strong nationalism and theological liberalism—the Ultramontanists were opposed by those, such as the Gallicans, who wished to restrict papal power. The Ultramontane Party triumphed in 1870 at the first Vatican Council when the dogma of papal infallibility was defined as a matter of Roman Catholic belief.