Although scientifically, a tomato is a fruit, it has also been held to be a vegetable. The confusion arises because scientists and nutritionists have different definitions!
Scientifically, if it grows on a plant and is the manner in which that plant gets seeds out into the world to reproduce, it’s a fruit. Pretty much anything that grows from a plant and has seeds falls into that category (e.g., apples, cucumbers, peppers, pumpkins, avocados and yes, tomatoes are all fruits scientifically speaking). If you look to the dictionary for the definition of ‘vegetable,’ that is the part of a plant or the whole plant. So, the confusion arises because in the kitchen, from a culinary viewpoint, most people classify fruits that fall on the savory side, like tomatoes, as vegetables. Even the USDA which, from a consumer viewpoint, uses nutrition as a benchmark, lists the tomato as a vegetable.
In 1893, the U.S. Supreme Court even tossed its view into the salad. The question that came before the court was whether imported tomatoes were subject to taxation under the Tariff Act of 1883. Since the act only applied to vegetables and not fruits, the legal conclusion would be critical to determining whether imported tomatoes would be inside our outside the scope of the tariff. The court sided with the veggies stating “Botanically speaking, tomatoes are the fruit of a vine, just as are cucumbers, squashes, beans, and peas,… ” “But in the common language of the people … all these are vegetables which are grown in kitchen gardens, and which, whether eaten cooked or raw, are, like potatoes, carrots, parsnips, turnips, beets, cauliflower, cabbage, celery, and lettuce, usually served at dinner in, with, or after the soup, fish, or meats which constitute the principal part of the repast, and not, like fruits generally, as dessert.”
About 100 years later, a quote attributed to journalist Miles Kington, may have summed up the debate best: “Knowledge is knowing that a tomato is a fruit. Wisdom is not putting it in a fruit salad.”