A small metal sculpture or label which decorates the very front of an automobile. It is usually placed on the hood of the car.
A hood ornament is often something as simple as the stylized logo of the automaker, but more complex ornaments are available, often as a specially-made replacement for another hood ornament.
I have seen hood ornaments in the shape of leaping horses, crouching panthers, and snarling wolves. I knew a guy in high school who had a water faucet as a hood ornament -- it actually worked and could be used to dispense water, lemonade, beer, or any other liquid when hooked up to a special tank in the trunk of the car.