The explanation lies in the two different ways that "fruit" is defined. First, it is true that scientifically speaking, tomatoes are fruits.

对“fruit（水果，果实）”的定义有两种不同说法。首先，从科学角度讲，番茄的确属于果实。

According to Merriam-Webster, a fruit is "the usually edible¹ reproductive body of a seed plant." In a blog post, the dictionary explained it in simpler terms: "Any thing that grows on a plant and is the means by which that plant gets its seeds out into the world is a fruit."

根据《韦氏词典》，果实通常指“种子植物的可食用繁殖体”。《韦氏词典》博客上的一篇文章给出了更简单的释义：“果实是长在植物上、能够将植物种子带到外面的部分。”

That definition includes apples, tomatoes, and anything else that grows from a plant and contains seeds. (Cucumbers, peppers, pumpkins², and avocados are all fruits too, according to science.)

这个定义包含了苹果、番茄等任何有种子的植物部位。从科学意义上讲，黄瓜、辣椒、南瓜、牛油果都属于果实。

Vegetables, on the other hand, have a slightly murkier³ definition. It's a word we use to group together a wide range of plants whose parts are edible and herbaceous, like roots, stems, and leaves. The critical distinction is that, according to the dictionary, a vegetable must be part of a plant or the whole plant itself, while fruits are just the means by which certain plants spread their seeds.

另一方面，蔬菜的定义要更模糊一些。我们把一大批具有根茎叶等可食草本部分的植物归类为蔬菜。根据《韦氏词典》，二者的关键区别是：蔬菜必须是植物的一部分或整体本身，而果实只是特定植物传播种子的方式。

"The thing a tomato plant produces isn't a part of the plant itself, any more than the egg a chicken lays is part of the chicken, or the apple is part of the tree on which it grew," Merriam-Webster wrote.

韦氏词典》称：“番茄不是植物本身的一部分，最多就像蛋与鸡、苹果与苹果树的关系一样。”

But the confusion arises because "vegetable" isn't a botanical classification so much as it is a culinary one. And "fruit" can be a culinary term, too — described as "having a sweet pulp⁴ associated with the seed" and "used chiefly in a dessert or sweet course," according to Merriam-Webster. So scientifically, fruits don't have to be sweet, but in the kitchen, most people would classify the fruits that fall on the savory⁵ side, like tomatoes, as vegetables.

但问题在于：“蔬菜”更多是一种烹饪分类，而不是一种植物学分类。与此同时，《韦氏词典》称，“fruit”也可以是一种烹饪食材，指“拥有带种子的甜果肉”、“主要用于甜点或甜食”的东西。也就是说，从科学角度，果实不必是甜的；但从烹饪角度，大多数人会根据果实的味道将其归类为蔬菜，比如番茄。

Nutritionists recognize the terms as they are commonly used, and tomatoes are listed as a vegetable under USDA guidelines.

营养学家根据番茄的主要用途将其列为蔬菜，而美国农业部的指导方针也将番茄列为蔬菜。

Even the Supreme⁶ Court has weighed in on the issue.

甚至连美国最高法院都曾介入过这个问题。

1883年3月3日，美国颁布了新的关税法，规定进口蔬菜需要缴纳10%的关税，而进口水果则不需要。当时纽约海关认为番茄是蔬菜，需交税。然而，商人约翰•尼克斯却认为，根据植物学定义，番茄属于水果，不应该被征税。于是，尼克斯直接将海关税收员告上法庭，要求退还被强制征收的税。

此案一路闹到了美国最高法院，直到6年后，法庭才做出最终裁定。法官认为：

"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, turnips⁷, beets⁸, cauliflower, cabbage, celery, and lettuce⁹, 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."

“从植物学上讲，番茄是藤本植物的果实，就像黄瓜、南瓜、黄豆、豌豆一样。但在人们的日常语言中，这些都是种在菜园里的蔬菜。它像土豆、胡萝卜、欧洲萝卜、芜菁、甜菜、菜花、卷心菜、芹菜、生菜一样，无论生吃还是熟吃，通常都是在晚餐里搭配着汤、鱼、肉食用。它是正餐的一部分，而不像水果一样，通常作为甜点。”

其实，蔬菜和水果本来就不是一个科学的分类，更像是一种习惯，没有确切的定论，所以，你开心就好。