The 'cloaca of Willis' refers to the anastomosis or junction of blood vessels located at the base of the brain, primarily comprising the circle of Willis. The circle of Willis is a complex network of arteries that supplies blood to the brain, ensuring adequate blood flow and equal distribution of oxygen and nutrients. While different terms are not commonly used as synonyms for the specific phrase 'cloaca of Willis,' it can be described as the arterial circle of Willis, Willis polygon, circle of Willis anastomosis, Willis's circle, or simply, Willis circle. These terms all refer to the same fundamental anatomical structure responsible for maintaining vital blood supply to the brain.