To really figure out if a tomato is a fruit or vegetable, you need to know what makes a fruit a fruit, and a vegetable a vegetable. The big question to ask is, DOES IT HAVE SEEDS? If the answer is yes, then technically, you have a FRUIT. This, of course, makes your tomato a fruit. It also makes cucumbers, squash, green beans and walnuts all fruits as well. VEGETABLES such as, radishes, celery, carrots, and lettuce do NOT have seeds (that are part of what we eat) and so they are grouped as vegetables. Now don't go looking for tomatoes next to the oranges in your grocery stores; fruits like tomatoes and green beans are usually (alas, incorrectly) referred to as "vegetables" in most grocery stores and cookbooks.