to burn something up: to set it on fire so that it is consumed or destroyed
This is the ordinary Hebrew word for burning something up. It always has an object, and the object is normally gone once the fire has done its work: a town reduced to rubble, an idol broken up and thrown in the flames, a leftover portion of sacrifice destroyed outside the camp, a scroll turned to ash. The same root means "to burn" in Ugaritic and in Akkadian, so the plain sense is secure.
The act turns up in strikingly different settings, and the setting rather than the word supplies the point:
- armies burning captured towns and enemy chariots
- priests burning what the law says may not be eaten or reused
- kings burning the idols and altars of other gods
- courts and mobs putting a condemned person to death by fire
- householders firing bricks or feeding a cooking fire
Hebrew has a separate word for burning something as an offering (קָטַר), which belongs to the altar and pictures smoke going up to God. This word carries none of that. When the priestly laws use it, they mean disposal: whatever has touched holy things and can never go back into everyday use is destroyed away from the sanctuary. So the same word describes a priest's duty and a conqueror's atrocity without shifting its sense.
The noun built on this word (שָׂרָף) means "a burning one," and it names the desert snakes whose bite burns as well as the winged attendants around God's throne in Isaiah's vision. Because the word always acts on something, scholars take that noun to name a creature that destroys by burning rather than one that merely glows.