A
solemnity is a
feast day of the
highest rank in the
liturgical calendar of the
Roman Rite, celebrating a mystery of faith such as the
Trinity, an event in the life of
Jesus, his mother
Mary, or another important
saint. The observance begins with the vigil on the evening before the actual date of the feast. Unlike feast days of the rank of feast (other than feasts of the Lord) or those of the rank of memorial, solemnities replace the celebration of
Sundays outside of Advent, Lent and Easter (those in
Ordinary Time).