Nut or Legume?

Just wondering while I eat these things called Peanuts, are they a Nut or Legume?

While “nut” is in their name, peanuts are in fact legumes. Did you know that Peanuts actually grow underground, as opposed to nuts like walnuts, almonds, etc. that grow on trees. 
Peanuts, belong to the single plant family, Leguminosae. Legumes are edible seeds enclosed in pods. As a group, they provide the best source of protein in the plant kingdom. Their nutritional benefits more closely resemble that of other legumes, their use in diets & cuisines are that of nuts.
From planting to harvesting, the growing cycle takes four to five months, depending on the type or variety.