In the culinary sense of these words, a fruit is usually any sweet-tasting plant product, especially those associated with seeds; a vegetable is any savoury or less sweet plant product; and a nut is any hard, oily, and shelled plant product.
These culinary vegetables that are botanically fruit include cucurbits (e.g., squash, pumpkin, and cucumber), tomatoes, peas, beans, corn, eggplant, and sweet pepper. In addition, some spices, such as allspice and chilies, are fruits, botanically speaking. In contrast, rhubarb is often referred to as a fruit, because it is used to make sweet desserts such as pies, though only the petiole of the rhubarb plant is edible. Edible gymnosperm seeds are often given fruit names, e.g., pine nuts, ginkgo nuts.
Botanically, a cereal grain, such as corn, wheat or rice, is also a kind of fruit, termed a caryopsis. However, the fruit wall is very thin, and is fused to the seed coat, so almost all of the edible grain is actually a seed.
Many common terms for seeds and fruit do not correspond to the botanical classifications. In botany, seeds are ripened ovules; fruits are the ripened ovaries or carpels that contain the seeds and a nut is a type of fruit and not a seed.
