From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Coffee_bean

A coffee bean is a seed of the coffee plant and the source for coffee. It is the pit inside the red or purple fruit often referred to as a cherry. Just like ordinary cherries, the coffee fruit is also a so-called stone fruit. Even though the coffee beans are seeds, they are referred to as “beans” because of their resemblance to true beans. The fruits – coffee cherries or coffee berries – most commonly contain two stones with their flat sides together. A small percentage of cherries contain a single seed, instead of the usual two. This is called a “peaberry“.