>Knowledge is knowing that tomatoes are fruits. Wisdom is not serving them in a fruit salad.
Botanically that is correct. Fruit is a general word for structures containing seeds, from apples and grapes to pomegranates and watermelons, but also cucumbers, walnuts and tomatoes.
|a fruit, watermelon|
HOWEVER...in the United States, tomatoes are vegetables.
In Nix vs. Hedden 1893 the U.S. Supreme Court ruled that tomatoes are vegetables, not fruit. An importer objected to the tarriff on vegetables being applied to the tomatoes he was bringing into the United States. The Port Authority of New York disagreed, and the case went through appeals up to the Supreme Court. There, the justice who heard the case ruled that common American usage should prevail and that vegetables were "usually served at dinner in, with, or after the soup, fish, or meats...and not, like fruits generally, as dessert." Thus, tomatoes were vegetables not fruits.
This ruling remains in place. I enjoy the idea that tomatoes may be fruits botanically and in the rest of the world (I don't know for sure), but in the United States they are vegetables.
Comments and corrections welcome.