The phrase "infernal regions" refers to the underworld or hell in many cultures. There are several synonyms for this term, including "Hades," "Tartarus," "Avernus," "Underworld," and "Hades' domain." Hades is the Greek god of the underworld and his domain is sometimes called the same name; Tartarus, another Greek mythological term, refers to the deepest, darkest part of the underworld where the wicked are punished; Avernus is a Latin term used by the Romans to refer to the entrance to the underworld; and the Underworld literally means the world beneath our own. These synonyms are often used in literature, mythology, and religious texts to describe the realm of the afterlife.