Despite their name, peanuts belong to the legume family (Leguminosae) along with other pulses such as peas, beans and lentils and, high oil content aside, share their nutritional characteristics.

They also have the healthy characteristics, particularly unsaturated fats, of tree nuts like walnuts and almonds. This double relationship is well expressed in the phrase "the nut that's really a bean".

What we know as a peanut is actually the kernel of the peanut plant and grows beneath the ground. There is a common misconception that peanuts grow on trees like other "nuts".

The botanical (taxonomic) name for peanuts is Arachis hypogaea, which may appear on some food and product labels. In the UK, peanuts are sometimes called "groundnuts" or, by some people "monkey nuts".