Humanity doesn't seem to have a universally accepted definition for that. Originally, colloquially, all the plants were vegetables that had edible parts. Later

Humanity doesn't seem to have a universally accepted definition for that. Originally, colloquially, all the plants were vegetables that had edible parts. Later fruits and vegetables had their own category, even though many of the fruits are not true fruits, some vegetables are actually fruits etc. It's a mess, as colloquial language usually is.