time to end this, I did some research.

Generally you can safely call the product of a fertilization a "fruit". (We
routinely, in the supermarket, call the structure bearing fruits "fruit").
Generally fruits will germinate into plants which will again flower,
offering another opportunity for fertilization. (Note that bananas we find
in the store bear tiny almost-remnants of seeds which will not
germinate...in the wild, banana "fruits" have seeds (fruits, being the
products of fertilization) which are much larger which will germinate). If
one discusses a part of a plant which is not the direct product of a
fertilization nor the structure bearing it, then one could safely call the
item an herb. For example, basil leaves are vegetative structures not
specifically the result of a fertilization and are most easily described as
herbs.

I do not have an adequate definition for 'vegetable', but my feeling for its
routine meaning is any part of a plant consumed whether a stem (celery), a
leaf (lettuce), a root or tuber (radish, or potato, respectively), and in
some cases the fruit of fertilization or structures bearing them (cucumbers,
yes-tomatoes). Add to this such items as mushrooms (basidiocarps of fungi)
and you get the idea....the term vegetable has come to mean most anything
which is not animal or mineral which we find in the 'produce' section of the
supermarket. Thus, the term vegetable has somewhat lost a botanical
usefulness in that there are more specific terms to use depending on the
particular structure being discussed.
so pretty much, a fruit IS a vegetable, and so is a banana leaf. yay


EDIT: or maybe not

Botanically speaking, anything that bears or is a seed is considered a fruit.
There are different kinds of fruit, ie nuts are a kind of
fruit. Vegetables
are any part of the plant that doesn't have to do with making new plants.
Lettuce is a leaf, carrot is a root, celery is a stem. I think I heard a
story of how the legal definition of a fruit vs. veggie was established as a
way of avoiding taxes or tarifs or something.
so a vegetable is any part of a plant that's not a fruit? hmm...