'Dark' in the Bible

They covered the surface of the entire land so that it was dark. They ate all the vegetation of the land and the fruit from the trees that the hail left. Nothing green was left on the trees or on the vegetation in all the land of Egypt.

And the Lord said to Moses, Let your hand be stretched out to heaven, and all the land of Egypt will be dark, so that men will be feeling their way about in the dark.

And when Moses' hand was stretched out, dark night came over all the land of Egypt for three days;

Keep it till the fourteenth day of the same month, when everyone who is of the children of Israel is to put it to death between sundown and dark.

It came between the Egyptian camp and the Israelite camp; it was a dark cloud and it lit up the night so that one camp did not come near the other the whole night.

And the people kept their places far off, but Moses went near to the dark cloud where God was.