Verses with the word solemn in the Old Testament (29 verses):

Leviticus 23:36
Seven days ye shall offer an offering made by fire unto the LORD: on the eighth day shall be an holy convocation unto you; and ye shall offer an offering made by fire unto the LORD: it is a solemn assembly; and ye shall do no servile work therein.

Numbers 10:10
Also in the day of your gladness, and in your solemn days, and in the beginnings of your months, ye shall blow with the trumpets over your burnt offerings, and over the sacrifices of your peace offerings; that they may be to you for a memorial before your God: I am the LORD your God.

Numbers 15:3
And will make an offering by fire unto the LORD, a burnt offering, or a sacrifice in performing a vow, or in a freewill offering, or in your solemn feasts, to make a sweet savour unto the LORD, of the herd or of the flock:

Numbers 29:35
On the eighth day ye shall have a solemn assembly: ye shall do no servile work therein:

Deuteronomy 16:8
Six days thou shalt eat unleavened bread: and on the seventh day shall be a solemn assembly to the LORD thy God: thou shalt do no work therein.

Deuteronomy 16:15
Seven days shalt thou keep a solemn feast unto the LORD thy God in the place which the LORD shall choose: because the LORD thy God shall bless thee in all thine increase, and in all the works of thine hands, therefore thou shalt surely rejoice.

2 Kings 10:20
And Jehu said, Proclaim a solemn assembly for Baal. And they proclaimed it.

2 Chronicles 2:4
Behold, I build an house to the name of the LORD my God, to dedicate it to him, and to burn before him sweet incense, and for the continual shewbread, and for the burnt offerings morning and evening, on the sabbaths, and on the new moons, and on the solemn feasts of the LORD our God. This is an ordinance for ever to Israel.

2 Chronicles 7:9
And in the eighth day they made a solemn assembly: for they kept the dedication of the altar seven days, and the feast seven days.

2 Chronicles 8:13
Even after a certain rate every day, offering according to the commandment of Moses, on the sabbaths, and on the new moons, and on the solemn feasts, three times in the year, even in the feast of unleavened bread, and in the feast of weeks, and in the feast of tabernacles.

Nehemiah 8:18
Also day by day, from the first day unto the last day, he read in the book of the law of God. And they kept the feast seven days; and on the eighth day was a solemn assembly, according unto the manner.

Psalms 81:3
Blow up the trumpet in the new moon, in the time appointed, on our solemn feast day.

Psalms 92:3
Upon an instrument of ten strings, and upon the psaltery; upon the harp with a solemn sound.

Isaiah 1:13
Bring no more vain oblations; incense is an abomination unto me; the new moons and sabbaths, the calling of assemblies, I cannot away with; it is iniquity, even the solemn meeting.

Lamentations 1:4
The ways of Zion do mourn, because none come to the solemn feasts: all her gates are desolate: her priests sigh, her virgins are afflicted, and she is in bitterness.

Lamentations 2:6
And he hath violently taken away his tabernacle, as if it were of a garden: he hath destroyed his places of the assembly: the LORD hath caused the solemn feasts and sabbaths to be forgotten in Zion, and hath despised in the indignation of his anger the king and the priest.

Lamentations 2:7
The LORD hath cast off his altar, he hath abhorred his sanctuary, he hath given up into the hand of the enemy the walls of her palaces; they have made a noise in the house of the LORD, as in the day of a solemn feast.

Lamentations 2:22
Thou hast called as in a solemn day my terrors round about, so that in the day of the LORD's anger none escaped nor remained: those that I have swaddled and brought up hath mine enemy consumed.

Ezekiel 36:38
As the holy flock, as the flock of Jerusalem in her solemn feasts; so shall the waste cities be filled with flocks of men: and they shall know that I am the LORD.

Ezekiel 46:9
But when the people of the land shall come before the LORD in the solemn feasts, he that entereth in by the way of the north gate to worship shall go out by the way of the south gate; and he that entereth by the way of the south gate shall go forth by the way of the north gate: he shall not return by the way of the gate whereby he came in, but shall go forth over against it.

Hosea 2:11
I will also cause all her mirth to cease, her feast days, her new moons, and her sabbaths, and all her solemn feasts.

Hosea 9:5
What will ye do in the solemn day, and in the day of the feast of the LORD?

Hosea 12:9
And I that am the LORD thy God from the land of Egypt will yet make thee to dwell in tabernacles, as in the days of the solemn feast.

Joel 1:14
Sanctify ye a fast, call a solemn assembly, gather the elders and all the inhabitants of the land into the house of the LORD your God, and cry unto the LORD,

Joel 2:15
Blow the trumpet in Zion, sanctify a fast, call a solemn assembly:

Amos 5:21
I hate, I despise your feast days, and I will not smell in your solemn assemblies.

Nahum 1:15
Behold upon the mountains the feet of him that bringeth good tidings, that publisheth peace! O Judah, keep thy solemn feasts, perform thy vows: for the wicked shall no more pass through thee; he is utterly cut off.

Zephaniah 3:18
I will gather them that are sorrowful for the solemn assembly, who are of thee, to whom the reproach of it was a burden.

Malachi 2:3
Behold, I will corrupt your seed, and spread dung upon your faces, even the dung of your solemn feasts; and one shall take you away with it.