'Solemnity' in the Bible

And Moses commanded them, saying, At the end of every seven years, in the solemnity of the year of release, in the feast of tabernacles,

So Jephthah went with the elders of Gilead, and the people appointed him head and military commander over them. Jephthah uttered everything he had to say with the solemnity of an oath in the LORD's presence at Mizpah.

Ye shall have a song, as in the night when a holy solemnity is kept; and gladness of heart, as when one goeth with a pipe to come into the mountain of the LORD, to the mighty One of Israel.