"belly," 1943, American English slang, probably from dialectal pronunciation of Italian la pancia "the belly," with the definite article absorbed, from Latin pantex (genitive panticis) "belly" (see paunch).
Entries linking to labonza
paunch n.
late 14c. paunce, "the human belly," from Old French pance (Old North French panche) "belly, stomach," from Latin panticem (nominative pantex) "belly, bowels" (source also of Spanish panza, Italian pancia); which is possibly related to panus "swelling" (see panic (n.2)). Earlier in English it meant "plate or mail armor worn to protect the belly" (early 14c.).