Beginning in the 17th century, botanists defined it as the organ that develops from the flower's ovary and surrounds the plant's seeds.
When the ovules are unfertilized, it is common to find that the ovary withers and does not come to maturity; but in the case of bananas, plantains and breadfruit, the...development of seeds seems to lead to a larger growth and a greater succulence of the fruit." "Vegetable..a general term from plants, and specifically, in language, of such plants as can be eaten by man...whether cooked or raw, and whether the whole or cuch are edible,or only the leaves of the roots or tubers, such edible or culinary plants or portions of plants, a distinction is made popularly between 'fruits' and 'vegetables,'..." ---Encyclopedia Britannica [Encyclopedia Britannica Company: New York] 11th edition, 1911  "Fruit. In the widest sense, any product of plant growth useful to man or woman, as grain, vegetable, cotton, flax, etc., 2.Even the United States Supreme Court has preferred the cook's definition over the botanists.In the 1890s, a New York food importer claimed duty-free status for a shipment of tomatoes, arguing that tomatoes were fruits, and so under the regulations of the time, not subject to import fees.Everett [Garland Publishing: New York] Volume 4, 1981 (p.1414) [NOTE: This book does not offer a separated definition for vegetable.]  "Vegetable took on its current sense just a few centuries ago, and essentially means a plant materials that is neither fruit nor seed. The word has both a technical and a common meaning.