nut

A dry indehiscent fruit that is usually shed as a one-seeded unit. It forms from more than one carpel but only one seed develops, the rest aborting. The pericarp is usually lignified and is often partially or completely surrounded by a *cupule. True nuts include the acorn, hazelnut, and beechnut. The term is often loosely applied to any woody fruit or seed, such as the walnut (which is a drupe) or the Brazil nut (which is a seed). Nutlets are small nuts and are typical of the Labiatae.