a fall and its wreckage: the crash of something tall or powerful coming down, and the fallen body or trunk left lying where it dropped
Hebrew builds this noun straight off the ordinary verb for falling (נָפַל) and keeps the verb's picture rather than softening it. Something that was standing is now down, and this one word can point either at the crash itself or at what is left on the ground afterward.
On the concrete side it is the body. Samson goes back to look at the fallen lion, and in Ezekiel the birds of the sky settle on the trunk of a great tree that has been cut down. English needs "carcass" for the animal and something like "fallen trunk" for the tree, but the Hebrew is one word in both places, and it names the thing by the fall that made it.
On the other side it is the fall as an event, and that is where Ezekiel puts it to work. Six of its eight appearances are in Ezekiel, most of them in his funeral songs over Tyre, Assyria, and Egypt, where coastlands shake at the sound of a city's fall and kings tremble on the day of Pharaoh's. Proverbs uses the same word for the collapse of the wicked that the righteous live to see. It is reserved for something big coming down, a sea power, an empire, a towering tree, and never for a person tripping on a step.
Two close neighbors are not the same word. The rubble a destroyed city is left as has its own term (מַפֵּלָה), naming the lasting heap rather than the coming down, and the usual word for a carcass as something unclean to touch (נְבֵלָה) names the dead body with no memory of how it dropped.