solemnity (n.) Look up solemnity at Dictionary.com
c. 1300, "observance of ceremony," from Old French solemnite, solempnete "celebration, high festival, church ceremony" and directly from Latin solemnitatem (nominative solemnitas) "a solemnity," from sollemnis (see solemn). Meaning "state of being solemn" is from 1712. Related: Solemnities.