Final answer:
In Sumerian belief, the afterlife is described as 'gloomy,' a contrast to other ancient cultures' more positive depictions. The Sumerian underworld, called Kur, was a place of dust and darkness, emphasizing a bleak existence. Hence, the correct term to describe it according to Sumerian beliefs would be 'gloomy.'
Step-by-step explanation:
The Sumerian belief system portrayed the afterlife as a rather somber and gloomy place. This view is markedly different from some other ancient cultures that might have depicted the afterlife as a place of joy or eternal reward. According to Sumerian mythology, the underworld was known as Kur and it was a dreary and dark place where spirits of the dead resided, quite distinct from a joyful or exciting vision of an afterlife.
The spirits were believed to eat dust and live in darkness. This stark depiction underscores the Sumerian view of life as a precious possession and the afterlife as an existence devoid of the pleasures experienced during life. Therefore, in the context of the Sumerian belief system, the adjective that best describes the afterlife is 'gloomy' , rather than 'happy', 'exciting', or 'scary'.