I guess the obvious place to start on this is by looking up the dictionary definition of "fruit". So, off to dictionary.com for a look, where we find that there are several definitions. However, the ones relevant to this subject are:
- the developed ovary of a seed plant with its contents and accessory parts, as the pea pod, nut, tomato, or pineapple.
- the edible part of a plant developed from a flower, with any accessory tissues, as the peach, mulberry, or banana.
By the strict botanical definition, then, a tomato is indeed a fruit. It comes from the flower of the tomato plant, and contains the seeds thereof. It is much the same as an apple, orange, lemon, or any of the other foodstuffs we would be happier defining as fruit. It is interesting to note, also, that according to this definition, peppers, cucumbers, and pea pods are also fruits, despite the fact that we would be more likely to categorize them as vegetables.
Out of interest, let's have a look at the definition for vegetable:
- any plant whose fruit, seeds, roots, tubers, bulbs, stems, leaves, or flower parts are used as food, as the tomato, bean, beet, potato, onion, asparagus, spinach, or cauliflower.
- the edible part of such a plant, as the tuber of the potato.
It seems that some of the "botanical" fruits are also included under the definition of vegetable by virtue of being edible. But when you are standing in your kitchen making a vegetable pie, you aren't too likely to include oranges, lemons or coconuts; there is an almost instinctive knowledge of what constitutes a fruit and what constitutes a vegetable. So the debate would seem to arise, really, from the difference between the scientific and the layman's understanding of edible foodstuffs. In everyday situations, we would be more inclined to name sweet foods as fruits, and savory ones as vegetables (which brings into question the identity of a sweet-potato!).
Scientifically speaking, tomatoes are fruit. But so long as the people you are speaking to know what you are talking about, you may as well call them fruit, vegetable, or anything else you like.