Soup legume is a term used to describe legumes that are commonly used in soups. The three most common soup legumes are LENTIL (6 letters), PEA (3 letters), and splitpea (8 letters). Lentils are small, lens-shaped legumes that come in a variety of colors and sizes. Peas are small, round legumes that are usually green or yellow in color. Splitpeas are peas that have been dried and split in half. All three of these legumes are popular ingredients in soups and stews.