Morning Star refers to Venus, which appears in the eastern sky at dawn. The King James Version translated this morning star as "Lucifer," and this is referred to as the name of Satan. However, other translations rendered it as the common "Venus."
Isa 14:12How you are fallen from heaven, O Morning Star, son of the dawn! How you are cut down to the ground, you who laid low the nations!Isa 14:13You said in your heart, ‘I will ascend to heaven; above the stars of God I will set my throne on high; I will sit on the mount of assembly in the far reaches of the north;Isa 14:14I will ascend above the heights of the clouds; I will make myself like the Most High.’Isa 14:15But you are brought down to Sheol, to the far reaches of the pit.
Isaiah (Prophet) likened this arrogant king of Babylon to this morning star. Furthermore, it is generally interpreted that this morning star symbolizes Satan.