solemnity
n. US //səˈɫɛmnəti// UK //sɒlˈɛmnɪti// solem·ni·ty
From 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.)