The name Zion in the Bible
Zion was originally a Jebusite stronghold located in or near Jerusalem or is equal to Jerusalem (2 Samuel 5:7). King David captures this stronghold and it is renamed City Of David. David sets up the tabernacle there and Solomon retrieves it from there to place the Ark and utensils in the temple. The prophet Isaiah mentions that YHWH dwells on Mount Zion (8:18) and later writers relate the name Zion to the eternal Jerusalem (Hebrews 12:22; spelled Σιων, Sion) and heaven (Revelation 14:1).
Etymology of the name Zion
Because Zion was originally not Israeli, the name Zion comes to us probably from a language other than Hebrew. HAW Theological Wordbook of the Old Testament mentions an Arabic root s-w-n, meaning to protect or defend, which may give Zion the meaning of fortress. Others (says HAW Theological Wordbook of the Old Testament) suggest derivation from a root saha, be bald.
Spelled the way it is, however, the name Zion is identical to the Hebrew word ציון (sayon) either meaning place of dryness, or monument:
On the Biblical canvass, the name Zion means Dry Place. Jones' Dictionary of Old Testament Proper Names reads Very Dry. NOBSE Study Bible Name List goes with the Arabic cognate mentioned above, and reads Fortress.