Plant definition, any member of the kingdom Plantae, comprising multicellular organisms that typically produce their own food from inorganic matter by the process of photosynthesis and that have more or less rigid cell walls containing cellulose, including vascular plants, mosses, liverworts, and hornworts: some classification schemes may include fungi, algae, bacteria, and certain single-celled eukaryotes that have plantlike...

plant noun (LIVING THING) A1 [ C ] a living thing that grows in earth, in water, or on other plants, usually has a stem, leaves, roots, and flowers, and produces seeds: native plants and animals. garden / greenhouse / indoor plants. a tomato plant. See also.