One of the hills on which Jerusalem stood. Used as a fortress, it was captured by David and renamed the Citadel of David (II Samuel 5:7). It assumed a sacred character when he brought the Ark to Zion. Gradually the name spread until it was applied to all of Jerusalem (II Kings 19:21; Psalms 125, 126). Indeed, increasingly it was used to mean the Jewish faith (Isaiah 33:20); hence, the term Zionism for the modern movement to make Palestine the Jewish homeland. Also spelled Sion.