The linea semilunaris is a term that refers to a curved line on the human abdomen. Synonyms for this line include the semilunar line, the arcuate line, and the Douglas line. This marking is formed where the abdominal muscles meet the connective tissue layer below the skin. The linea semilunaris runs laterally along both sides of the rectus abdominis muscle, from the pubic symphysis to the costal cartilages. The prominence of this line can vary from person to person, but it is an important anatomical landmark that can aid in locating abdominal organs during medical exams and surgeries.