Zion (Hebrew: ציון) (also transliterated Sion, Tzion or Tsion) is a place name often used as a synonym for Jerusalem. The word is first found in Samuel II, 5:7 dating to c.630–540 BCE according to modern scholarship. It commonly referred to a specific mountain near Jerusalem (Mount Zion), on which stood a Jebusite fortress of the same name that was conquered by David and was named the City of David. The term Tzion came to designate the area of Jerusalem where the fortress stood, and later became a metonym for Solomon's Temple in Jerusalem, the city of Jerusalem and generally, the World to Come.
Read more about Zion.