Why is a coconut a drupe rather than a true botanical nut?

In botanical terms, a coconut is classified as a drupe rather than a true nut because of its structural development and the composition of its pericarp (the ripened ovary wall).12

While the term "nut" is often used in culinary contexts to describe hard-shelled, oily seeds, a true botanical nut is defined as a dry, indehiscent fruit that develops from more than one carpel and possesses a tough, woody wall.32

In contrast, a coconut is a simple, fleshy fruit derived from a single ovary. It is categorized as a drupe because its pericarp is differentiated into distinct layers:1
* Exocarp: The outer skin or peel.1
* Mesocarp: A thick, fibrous layer (the husk).14
* Endocarp: A hard, stony inner layer (the shell) that encloses the seed.12

Because the coconut features this fibrous middle layer and a stony endocarp, it fits the botanical definition of a drupe, similar to other fruits like peaches, cherries, and almonds, rather than the dry, woody structure of a true nut.12