solemnity

Etymology

solemn + -ity, from Middle English solemnity (“observance of formality and ceremony”), frequently in the phrases in solemnity, with solemnity, which from Old French solemnite, from Latin sollemnitās, from sollemnis. (Compare solemn.)

noun

1. The quality of being deeply serious and sober or solemn.
   the solemnity of a funeral
   These promises were often made with great solemnity and confirmed with an oath. 1754, Jonathan Edwards, An Inquiry into the Modern Prevailing Notions Respecting that Freedom of the Will which is supposed to be Essential to Moral Agency
2. An instance or example of solemn behavior; a rite or ceremony performed with reverence.
3. (Catholicism) A feast day of the highest rank celebrating a mystery of faith such as the Trinity, an event in the life of Jesus, the Virgin Mary, or another important saint.
4. (law) A solemn or formal observance; proceeding according to due form; the formality which is necessary to render a thing done valid.
5. (obsolete) A celebration or festivity.