What is "vologash"

Wolgash or Vologash was a king of Hatra, an ancient city in nowadays Iraq. He is known from more than 20 inscriptions found at Hatra and reigned from about AD 140 to 180. He was the son of Naṣru who reigned from about AD 128 to 140. He was one of the first rulers of Hatra calling himself mlk (king), but he bears also the title ''mry' '' (lord). Both titles are also attested for his brother Sanatruq I. It is unclear whether they both reigned together and took the title king at some point in their reign, or whether Sanatruq succeeded Wolgash. His successor was either his brother or his nephew Abdsamiya.