No wlasnie! (bardzo polskie powiedzanko :) staram sie)
Belly and stomach can also fall into similar categories of meaning. Don't get excited, I said similar ok? Obviously, the reference to stomach is not always anatomical or medical, but "belly" is rarely used in a medical or anatomical context. :)
Aside: possibly the most difficult word for an English speaking person to translate would probably be "friend". Very nuanced and confusing for us to truly understand.