The word `` vegetable '' can also be used to mean plants in general , such as when people say `` Animal , Vegetable , or Mineral . '' As an adjective , the word vegetable is used in scientific and technical contexts with a different and much broader meaning , namely of `` related to plants '' in general , edible or not â '' as in vegetable matter , vegetable kingdom , vegetable origin , etc. . The meaning of `` vegetable '' as `` plant grown for food '' was not established until the 18th century .