Water pepper is an herbaceous perennial plant known for its medicinal properties. It has several synonyms such as smartweed, biting pepper, and knotgrass. Smartweed is used to describe its sharp and pungent taste while biting pepper refers to its peppery flavor. The name knotgrass is given due to the plant's tendency to grow in knots. Other synonyms for water pepper include lady's thumb, pinkheart smartweed, and red leg. Lady's thumb refers to the plant's distinct thumb-like marking on the leaves while pinkheart smartweed denotes its pink-colored flowers. Additionally, water pepper is also known as Polygonum hydropiper, reflecting its scientific classification.