hopper car

noun

1. a person or thing that hops
2. any hopping insect, esp. a grasshopper
3. a box, tank, rail car, etc., often funnel-shaped, from which the contents can be emptied slowly and evenly: the hopper of an automatic coal stoker
4. ☆ a freight car with a bottom that opens to unload freight
   in full hopper car
5. a box into which legislative bills are dropped for introduction, assignment to committees, etc.: often used figuratively