Ultramontanism effectivly means active Catholicism, because it recognizes as its head the Pope over the authority of local temporal or spiritual hierarchies. The term means dweller beyond the mountains (ultra montes), that is beyond the Alps - referring to the Pope in Rome. The actual term is relative and technical ecclesiastical language actually applies the word in this sense. In the Middle Ages, when a non-Italian pope was elected he was said to be a papa ultramontano.

The word was revived after the Protestant Reformation. Among the northern European governments and peoples there gradually developed an tendency to regard the papacy as a foreign power. This name of Ultramontane was applied to the supporters of the Roman doctrines, as they were supposed to renounce "Gallican liberties" in favour of the head of the Church. The term was intended to be insulting, or at least to convey the implication of a failing in attachment to one's own country. From the 17th century, ultramontanism became closely associated with the Society of Jesus, stating the superiority of popes over councils and kings, even in temporal questions.

In the 18th century the word passed to Germany (Josephinism and Febronianism), where it acquired a much wider signification, being applicable to all the conflicts between Church and State, the supporters of the Church being called Ultramontanes. The Vatican Council issued numerous written attacks upon Ultramontanism.

The great triumph of Ultramontanism came at the First Vatican Council with the pronouncement of papal infallibility.