'Son' in the Bible

"But you, his son Belshazzar, have not humbled yourself, although you knew all this.

I was watching in the night visions, "And with the clouds of the sky one like a son of man was approaching. He went up to the Ancient of Days and was escorted before him.

So he approached the place where I was standing. As he came, I felt terrified and fell flat on the ground. Then he said to me, "Understand, son of man, that the vision pertains to the time of the end."

In the first year of Darius son of Ahasuerus, who was of Median descent and who had been appointed king over the Babylonian empire --