What do we call the ceremony of officially making someone a saint?

The story behind the answer

This is the Church’s formal act of declaring someone a saint by adding them to the official canon of saints, after a lengthy inquiry into their life, virtues, and miracles. The proclamation is made by the pope during a solemn liturgy; a feast day is assigned and the person is permitted universal veneration. That’s different from beatification (a step allowing local or regional veneration), consecration (dedicating a person or thing to sacred use, like a church or bishop), and sanctification (the general process of becoming holy).

In the Middle Ages, rising papal authority standardized this process: from the 12th–13th centuries, only the pope could issue the final decree, replacing earlier local acclamations. Meticulous verification of posthumous miracles, pilgrim traffic to shrines, and the politics of relics all shaped who attained the honor and how their cults spread across Christendom.