While it's widely assumed to be a vegetable, botanists know a tomato is really a fruit.
There are other fruits that are considered to be vegetables based on perception as well.
Olives are a fruit because they come from the flower of the olive tree. Not only are eggplants considered fruits, they're specifically berries.
All types of squash, including pumpkins, start from a flower on a vine, so they're technically fruits too.