Solemn Mass (Latin: missa solemnis) is the full ceremonial form of a Mass, predominantly associated with the Tridentine Mass where it is celebrated by a priest with a deacon and a subdeacon, requiring most of the parts of the Mass to be sung, and the use of incense. It is also called High Mass or Solemn High Mass.
The High Mass in the Extraordinary Form is a solemn and rich liturgical celebration in the Traditional Latin Rite, reflecting the Church's ancient traditions. It includes the sprinkling of Holy Water, the Gradual, Alleluia, or Tract, the Gospel, the Homily, the Credo, and the use of incense. The High Mass is filled with rich symbolism, solemn actions, and deep theological meaning, serving to glorify God and draw the faithful closer to the mystery of Christ's sacrifice.