A solemnity is a principal day in the Church's liturgical calendar. Solemnities celebrate events in the life of Christ, Mary, and the saints which are of particular importance for the whole Church, Celebration of these special days begins the evening before. The following days are solemnities: January 1 Sunday between January 2 and January 8 March 19 March 25 March/April (date varies) 40 days after Easter 50 days after Easter Sunday after Pentecost Sunday after Holy Trinity Friday after Body and Blood of Christ June 24 June 29 August 15 November 1 November (date varies, but always Sunday) December 8 December 25 Mary, Mother of God Epiphany Joseph, Husband of Mary Annunciation Easter Triduum Ascension of the Lord Pentecost Holy Trinity Body and Blood of Christ Sacred Heart Birth of John the Baptist Peter and Paul, Apostles Assumption of the Blessed Virgin All Saints Christ the King Immaculate Conception Christmas (Birth of the Lord)

a principal day with the highest rank in the liturgical calendar.

A Solemnity of the Roman Catholic Church is a principal holy day in the liturgical calendar, usually commemorating an event in the life of Jesus, Mary, or the saints. The observance begins in the evening prior to the actual date.

Ceremoniousness; impressiveness; seriousness; grave earnestness; formal dignity; gravity.

Hence, affected gravity or seriousness.

a trait of dignified seriousness

A rite or ceremony performed with religious reverence; religious or ritual ceremony; as, the solemnity of a funeral, a sacrament.

ceremony adapted to impress with awe.

Solemn state or feeling; awe or reverence; also, that which produces such a feeling; as, the solemnity of an audience; the solemnity of Westminster Abbey.

A solemn or formal observance; proceeding according to due form; the formality which is necessary to render a thing done valid.

sol lem'na ti formality