Botanically, a plant which is any member of the taxonomic kingdom Plantae. Informally, any part of a plant that is eaten by humans as part of a savoury dish and that is not a fruit, seed, or cereal grain. The usage is often inconsistent. For instance, aubergines, bell peppers (capsicums), and tomatoes are commonly considered vegetables, but in fact are fruits, while rhubarb is treated as fruit although it is the stem of the plant.