'Solemn' in the Bible

So the Apostles, after giving a solemn charge and delivering the Lord's Message, travelled back to Jerusalem, making known the Good News also in many of the Samaritan villages.

He commanded us to preach to the people [both Jew and Gentile], and to solemnly testify that He is the One who has been appointed and ordained by God as Judge of the living and the dead.

These men went to the chief priests and elders and said, “We have bound ourselves under a solemn curse that we won’t eat anything until we have killed Paul.

So they arranged a day with him and came to him in considerable numbers at the house of the friends who were entertaining him. And then, with solemn earnestness, he explained to them the subject of the Kingdom of God, endeavouring from morning till evening to convince them about Jesus, both from the Law of Moses and from the Prophets.