'Master' in the Bible

Some men from Manasseh joined David when he went with the Philistines to fight against Saul. (But in the end they did not help the Philistines because, after taking counsel, the Philistine lords sent David away, saying: "It would be disastrous for us if he deserts to his master Saul.")

Joab replied, "May the Lord make his army a hundred times larger! My master, O king, do not all of them serve my master? Why does my master want to do this? Why bring judgment on Israel?"

Ornan told David, "You can have it! My master, the king, may do what he wants. Look, I am giving you the oxen for burnt sacrifices, the threshing sledges for wood, and the wheat for an offering. I give it all to you."