Leguminous is the adjective for plants like beans and peas: plants that grow their seeds in a pod. A teacher or a science book might say “leguminous plants” or “a leguminous crop.” Farmers like them because these plants can put goodness back into the soil and help the next crop — though you cannot see that happening. The word is formal. You will almost never hear it at the dinner table; there people just say beans, peas, or “this kind of plant.” It describes the plant. It is not itself the name of the plant.