We have all come across these terms. And frankly speaking, they can be confusing. For example, the tomato can sometimes be considered a bit of both fruit and vegetable and some books consider a banana herb and not a fruit. But is there a clear cut definition?
Botanically speaking, anything that bears a seed or is a seed is considered a fruit. There are different kinds of fruit, i.e. 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, and 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 tariffs or something.
Technically, a tomato is a berry. Just for further enjoyment, an apple is a fluid-filled hypanthium. The particular item you are discussing will determine the specific best term to describe it. Generally you can safely call the product of fertilization a “fruit”. (In the supermarket we routinely 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 fertilization or 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 fertilization and are most easily described as herbs. We do not have an adequate definition for ‘vegetable’, but our 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). Added to this are items such as mushrooms (basidiocarps of fungi) and you get the idea….the term vegetable has come to mean almost 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. Note that there are specific botanical definitions for berries which can be found in any good plant classification text; you can see this is essential, for example, in distinguishing between raspberries, blueberries, and tomatoes (also berries). We hope this shed some light on the challenge of plant classification and gives some insight as to why scientific names were established to pin down a particular organism to prevent confusion with many common names or possibly similar terms for different organisms.