is a peanut really a nut?

Answer 1

No, the peanut is actually a legume and in the same family as string beans, lima beans and peas. It is an unusual member of that family because the plant flowers above ground, but upon fertilization of the flower, the flower "head" begins a downward journey until it burrows itself into the soil. There, it forms the peanut which is a seed.

Answer 2

No the peanut is a legume. In the bean family.
Peanuts are also known as earthnuts, goobers, goober peas, pindas, jack nuts, pinders, manila nuts and monkey nuts (the last of these is often used to mean the entire pod, not just the seeds).