'Dark' in the Bible

And when it was the time for shutting the doors at dark, they went out; I have no idea where the men went: but if you go after them quickly, you will overtake them.

And at their cry, the Lord made it dark between you and the Egyptians, and made the sea go over them, covering them with its waters; your eyes have seen what I did in Egypt: then for a long time you were living in the waste land.