fire: burning flame and its heat and light, whether an ordinary blaze or the fire that marks God's presence, worship, or judgment.
This is the ordinary word for fire, and it never stops meaning fire. The same word covers the cooking flame, the burning bush, the fire on the altar, the lightning of a storm, and the blaze of God's anger. Hebrew does not switch to a different word for these; it lets one word carry the whole range, and the setting tells you which kind of fire is in view.
What ties the uses together is what fire does: it consumes, it purifies, it gives light and heat, and it cannot be touched or controlled. Those qualities are why fire became such a natural picture in Israel's worship and prophecy. The fire that lights a hearth is the same fire that burns up an offering, the same fire that falls from heaven, and the same fire the prophets use to describe God's judgment falling on a city.
Because of this, fire sits very close to God himself in the Bible. God appears in fire, speaks from fire, and is even called a consuming fire, yet he is never simply identified with it. The reader has to feel the difference between a literal campfire and the fire that signals God is present or that his judgment has arrived, because the word itself does not mark the difference.