My son wants to know if tomatoes are fruit or vegetables, for certain.
He’s out of luck then, because there is no certain answer. Tomatoes are botanically a fruit, but in culinary usage they are classified as a vegetable.
There have been any number of threads on this subject before.
Why can’t they be both, in the same way as bell peppers (capsicums) are?
Exactly. Spinach is a leaf and a vegetable, carrots are a root and a vegetable, cauliflower is a flower and a vegetable – and tomatoes are a fruit and a vegetable.
I learned in a biology class at some point in my misspent youth that it’s something along the lines of “a fleshy body surrounding a plant’s seeds.” Which sounds acceptably similar to Webster’s definition. Of course, a vegetable can be any portion of a plant. So all fruits are vegetables, though not all vegetables are fruits.
For cooking purposes, at least in this country, we treat tomatoes, peppers, green beans, and squashes as “vegetables”, a category we consider distinct from “fruits”. But all four of those things are, biologically speaking, fruits. We tend only to consider fruits with a predominantly sweet flavor to be fruits for the purposes of cooking and eating. But this is a cultural definition, not a biological one.
I believe for the purposes of taxation, however, tomatoes are treated as vegetables, again since they are consider such by the popular conception. It’s important to realize that popular ideas about things are often different from technical ones - after all, we silly members of the public think of strawberries as fruits, when technically they’re nothing but fleshy bits of stem. (Or so I’ve read.)
Interestingly, carrots are also fruit, according to European law. Some countries make carrot jam. Jam has to have a certain minimum fruit content. Carrots are used like fruit, so legally they are fruit.
Or maybe that isn’t interesting.