QUOTE(Serendipity @ Jun 29 2008, 12:19 AM)

I think of it as a fruit, but it's not like you're going to take a whole tomato to school to eat as a snack. =p
I eat tomatoes as snacks. The littler ones, not the big ones. Roma tomatoes are excellent to just eat 'cos their flavor is a little more robust.
So, definitions of each term, according to the Oxford English Dictionary:
Tomato - The
glossy fleshy fruit of a solanaceous plant (Solanum Lycopersicum or Lycopersicum esculentum), a native of tropical America,
now cultivated as a garden vegetable in temperate as well as tropical lands.
Fruit - The edible product of a plant or tree, consisting of the seed and its envelope, esp. the latter when it is of a juicy pulpy nature, as in the apple, orange, plum, etc.
Vegetable -
A plant cultivated for food; esp. an edible herb or root used for human consumption and commonly eaten, either cooked or raw, with meat or other article of food.
Also, according to the
Columbia Encyclopedia:
QUOTE
There is no clear botanical distinction between vegetables and fruits. Most vegetables consist largely of water, making them low in calories. They are excellent sources of fiber, vitamins A and C, potassium, calcium, and iron.
Therefore, the difference between a fruit and a vegetable seems to be the latter's link to commodification (see the italicized part in the definition of
vegetable).