Another classic battle of who's right, right? Well, corn is indeed a fruit - in fact, many, many fruits.
If you use the botanists' oh-so-appetizing definition of a fruit as, "the edible plant structure of a mature ovary of a flowering plant," you realize that an average ear of corn is actually 600 to 800 little fruits attached to a woody, inedible core, the cob.
To continue the lose-your-appetite description, a corn kernel is a small embryonic plant with a large food supply of storage proteins and starch, wrapped in a layer of fiber called the pericarp. You can refer to the entire kernel as a seed, and indeed, the whole kernel is planted, but like a yolk in an egg, the germ in the center of the kernel is the seed that grows into another corn plant. The pericarp, like the eggshell, offers protection. The watery, starchy endosperm, like the egg white, is the source of energy and protein for the seed. We have to leave the egg metaphor to discuss the other bit of the corn kernel, the tip cap, which is where the kernel attaches to the cob, and through which the kernel gets its food and water from the cob, much like, yes, an umbilical cord.
While we're on the subject, tomatoes, peppers, snap beans, cucumbers, and eggplants are some of the other non-traditional fruits that we think of as vegetables. Bananas, though, are not.