Introibo /ˈɪntɹəʊiːbəʊ/ noun1 •The prayers spoken by the priest at the foot of the altar at the start of a Tridentine Mass.At the Introibo he noticed at his right, as usual, his guardian angel, who acted as the angel mentioned by St. John in the Apocalypse, standing before the altar and bearing a golden censer. — 1959
