serpent: a snake, the limbless reptile, used both for the literal creature and as a vivid image of danger, cunning, and cosmic evil
This is one word for one creature, the snake, and every place it appears it names a serpent. What changes is not the meaning but the role the snake plays in the scene. Most often it is simply the animal:
- the thing that bites in the wilderness
- that hides in a wall
- that strikes when wine is drunk
- that an outlaw tribe is compared to
The Bible knows the snake first as a real and dangerous creature.
From that hard fact the writers draw their pictures. Because a snake is quiet, quick, and deadly, it becomes the natural image for a hidden threat, for poison in the mouth, and for a cunning that can ruin a person before they see it coming. The serpent of the garden in Genesis 3 is the most famous case: a beast of the field marked out only by its shrewdness, who talks its way into the first human sin.
Two special uses stretch the same word further. In the wilderness Moses lifts up a bronze snake on a pole so that the bitten may look and live, an object Israel later turns into an idol and Hezekiah destroys. And in the poetry of Isaiah, Job, and Amos the serpent swells into a cosmic monster, the twisting sea-dragon Leviathan that God alone can master. The word never stops meaning snake. The danger it names simply grows from a bite in the dust to an enemy at the bottom of the sea.