the belly; the stomach. I hit him, pow, right in the breadbasket.

What does being the breadbasket mean?

It can refer to the stomach as an actual digestive organ ("his breadbasket rumbled with hunger"), but these days it's more commonly applied to the general stomach area ("rested her hands on her breadbasket").

Where did the term bread basket come from?

bread-basket (n.)

1550s, "basket for holding bread," from bread (n.) + basket (n.). Slang meaning "belly, stomach" is attested from 1753, especially in pugilism. Another slang term for the belly was pudding-house (1590s).