From a botanical standpoint—that’s what the nerds in lab coats care about—a fruit is the mature ovary of a flowering plant. Yeah, I know that sounds like a line from a sci-fi romance, but stick with me. If it develops from a flower and contains seeds, it’s a fruit. Peppers? Fruit. Cucumbers? Fruit. Those little green beans you had for dinner? Fruit, baby.
This means the entire produce aisle is basically a botanical lie. Vegetables, on the other hand, are everything else: roots (carrots), stems (celery), leaves (spinach), and flowers (broccoli). So by this logic, a tomato is a fruit, but a rhubarb stalk is a vegetable—even though rhubarb is technically a leaf stem. Nature loves a loophole.
