ʾÛr refers to fire or its light — the luminous, burning aspect of flame. It is related to the more common ʾôr (H216/H215) meaning 'light,' sharing the same root. The word appears in contexts of literal fire (Isaiah 31:9; 50:11) as well as divine theophany and heavenly radiance. The famous phrase 'Ur of the Chaldeans' — Abraham's homeland — may also derive from this root, suggesting 'city of fire/light.' The word captures fire's dual nature: destructive power and illuminating glory.
Fire is one of the most significant symbols in Hebrew theology. God appears in fire — to Moses at the burning bush (Exodus 3), to Israel as a pillar of fire (Exodus 13), at Sinai (Exodus 19), and to Elijah on Carmel. Fire represents divine holiness that both purifies and consumes. Isaiah 10:17 calls God himself 'the Light [ʾôr] of Israel' who will become 'a fire' to devour enemies. Ezekiel's visions of divine glory are saturated with fire imagery. The same theme runs into the New Testament: Jesus is the Light of the world (John 8:12), and at Pentecost the Spirit descends as 'tongues of fire.'