The name “Peanut” is just simply a name derived from the observation of the peanut. When the plant was ‘discovered’ by Europeans, it was believed to be a nut (when in fact it is a woody legume, or bean), and they noticed that it grows in a pod, like peas do. Therefore it is a nut like a pea, or a peanut.
The scientific name for the peanut is Arachis Hypogaea. It has also been called other names in its history