Birtum
Birtum was a Mesopotamian god who was the husband of Nungal. He was regarded as a deity associated with the underworld.
Character
Birtum's name means "fetter" or "shackle" in Akkadian, and he was likely a deification of such objects. While the word is grammatically feminine, the deity was regarded as male. A similar word, birdu, is etymologically unrelated to his name.In god lists he appears in the circle of Nergal as one of the gods associated with the underworld.
Associations with other deities
Birtum was the husband of Nungal, the goddess of prisons. It has been proposed that he was a son of Enlil, as his wife was on occasion addressed as the daughter in law of this god.His sukkal was the god Eturammi, whose name means "do not slacken." It is assumed that he was one of the sukkals who were simply personification of specific commands of their masters, similar to Id's sukkal Nēr-ē-tagmil or Nergal's sukkal Ugur.
Birtum could be regarded as a twin brother of the god Šarrab, though sometimes the latter is instead paired with Šâbu instead. The former tradition is documented in the god list An = Anum. The names of both Birtum and Šarrabu could be written logographically as dKAL.EDIN, which literally meant "youngster of the steppe" or "strong one of the steppe." Šarrabu itself might mean "cheater" or "slanderer," though other possibilities have also been proposed, including a possible association with the Arabic word sārab, "Fata Morgana." In a single source the names of the pair are explained as "Lugal-irra and Meslamta-ea of MAR.KI"