Vegetable is a culinary term denoting any part of a herbaceous plant that can be eaten whole or in part. It is commonly consumed by humans as food.

These include leaf vegetables (e.g. lettuce), stem vegetables (asparagus), root vegetables (carrot) and flower vegetables (broccoli), and botanical fruits such as cucumbers, squashes, pumpkins, avocados, capsicums, et cetera, as well as botanical pulses like green beans, and fleshy, immature seeds such as those of peas or beans.

In general, vegetables are thought of as being savoury, and not sweet (with some exceptions, such as rhubarb and pumpkin).

Commercial production of vegetables is a branch of horticulture called olericulture.

Word Origin

Vegetable is also used as a literary term for any plant: vegetable matter, vegetable kingdom. It comes from Latin vegetabilis (animated) and from vegetare (enliven) in reference to the process of a plant growing. It wasn't until the 15th century when the word Vegetable was first used in print. And not until the 18th century when the word was used as a noun refering directly to the category of plants.

Cite: Wikipedia