Vegetable
Vegetable is a culinary term denoting any part of a plant that is commonly consumed by humans as food, but is not regarded as a culinary grain, fruit, nut, herb, or spice.
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.
Vegetable is not a botanical term and so there is no contradiction in a plant part being a fruit botanically while still being considered a vegetable (see diagram).
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.
Vegetable is also used as a literary term for any plant: vegetable matter, vegetable kingdom.