We've all heard someone say this at one point..."Did you know that a tomato is really a fruit?" Botanically speaking, tomatoes are indeed fruit, as well as, cucumbers, peppers, and anything with seeds inside it.
A broad definition from Wikipedia: a fruit is a structure of a plant that contains its seeds.
The fleshy part is a trick to encourage animals (including us) to eat seeds and in-turn disperse them. You know, the plant kingdom has to survive somehow.
So what exactly is a "vegetable"? Check in tomorrow.