'Lord' in the Bible

Joab said, "May Yahweh make his people a hundred times as many as they are. But, my lord the king, aren't they all my lord's servants? Why does my lord require this thing? Why will he be a cause of guilt to Israel?"

Ornan said to David, "Take it for yourself, and let my lord the king do that which is good in his eyes. Behold, I give the oxen for burnt offerings, and the threshing instruments for wood, and the wheat for the meal offering. I give it all."