Peter Canisius, Saint (kənĭshˈēəs) [key], 1521–97, Dutch Jesuit, Doctor of the Church, b. Nijmegen. He spent his life traveling widely strengthening wavering Roman Catholics, preaching, and instructing. He was one of the most vigorous of the Catholic preachers in the regions affected by Lutheranism, above all in W and S Germany. St. Peter wrote much; his catechism was especially important and was one of the earliest popular expositions of the faith. Feast: Apr. 27.