The words “Zion” and “Mount Zion” were first used to talk about the place that King David took from the Jebusites (see: 2 Samuel 5:7). After King David took this place, the words “Zion” and “Mount Zion” were used to talk about Jerusalem (see: 1 Kings 8:1; Isaiah 28:16).
The word “Zion” was also used in several other ways. It was used to talk about the temple in Jerusalem. It was used to talk about the people of God. It was also used to talk about the new, heavenly Jerusalem that God will create (see: Hebrews 12:22; Revelation 14:1; see also Galatians 4:26; Revelation 3:12).