1. the hill on which the higher and more ancient part of Jerusalem was built (דָּוִד עִיר, city of David, because David captured it); it was the southwesternmost and highest of the hills on which the city stood; (many now would identify it with the eastern hill, some with the northern; cf. Furrer in Schenkel iii. 216ff; Mühlau in Riehm, under the word; per contra Wolcott in B. D. American edition, under the word; Schultz in Herzog edition 2 vi., p. 543f).

2. used very often for the entire city of Jerusalem itself: Romans 9:33 and 1 Peter 2:6 (after Isaiah 28:16); Romans 11:26 (from Isaiah 59:20); ἡ θυγάτηρ Σιών (see θυγάτηρ, b.β'.), Matthew 21:5; John 12:15.

3. Since Jerusalem, because the temple stood there, was called the dwelling-place of God (cf. Matthew 5:35; κύριος τήν Σιών ᾑρετίσατο εἰς κατοικίαν ἑαυτῷ, Psalm 131:13 ()), the expression τό Σιών ὄρος is transferred to heaven, as the true dwelling-place of God and heavenly beings, the antitype of the earthly Zion: Hebrews 12:22; Revelation 14:1.

Of Hebrew origin (Tsiyown); Sion (i.e. Tsijon), a hill of Jerusalem; figuratively, the Church (militant or triumphant) -- Sion.

see HEBREW Tsiyown