Meaning

1. A participant in a boxing match; a fighter who boxes.
2. A breed of stocky, medium-sized, short-haired dog with a square-jawed muzzle.
3. A type of internal combustion engine in which cylinders are arranged in two banks on either side of a single crankshaft.
4. The person running a game of two-up.
5. One who packs boxes.
6. A letterboxer.
7. Attributive form of boxers (“boxer shorts”).