feast in honour of the Trinity. It is celebrated in the Christian churches on the Sunday following Pentecost (the 50th day after Easter). It is known that the feast was celebrated on this day from as early as the 10th century. Celebration of the feast gradually spread in the churches of northern Europe, and in 1334 Pope John XXII approved it for the entire church. In the liturgical Church Year, Anglican and Lutheran churches date the Sundays that follow Trinity "after Trinity"; the Roman liturgy dates these Sundays "after Pentecost."