A tomato grows from a tomato flower and is full of seeds, which makes it a fruit by every scientific definition. Specifically, itβs a berry - just like bananas, grapes, and kiwis. Cucumbers, peppers, pumpkins, and zucchinis are also fruits by this rule.
So why do we treat tomatoes like vegetables? Because they taste savory and we use them in salads, sauces, and sandwiches instead of desserts. In 1893, a US importer tried to argue that tomatoes were fruit so he wouldnβt have to pay the import tax that applied only to vegetables.
The case went all the way to the US Supreme Court. The judges agreed that tomatoes are botanically fruit, but ruled that in everyday English they count as vegetables - and so they would be taxed that way. So tomatoes are scientifically fruit and legally vegetables, all at once.