Stacker

Noun

1. Any person or thing that stacks. A worker who stacks the shelves in a supermarket. A participant in sport stacking.
2. A worker who stacks the shelves in a supermarket.
3. A participant in sport stacking.
4. Any device allowing items to be stacked.

   "a spring-loaded plate stacker in a cafeteria"

5. An output bin in a document feeding or punch card machine (contrast with hopper).