A metal box about the size of a lunchbox (or in some models a large wastebasket), for collecting the {chad} (sense 2) that accumulated in {Iron Age} card punches. You had to open the covers of the card punch periodically and empty the chad box. The {bit bucket} was notionally the equivalent device in the CPU enclosure, which was typically across the room in another great gray-and-blue box.
[glossary]
[Reference(s) to this entry by made by: {bit bucket}{punched card}]