() is a title and military rank of Iranian origin, a compound of ("head, chief") and ("regiment"). In modern usage in Iran, is the equivalent of colonel.
The origin of the title may date back at least to the Parthian period. In the Sasanian period, it was a rank in the hierarchy of the cavalry force. In the medieval period, has been defined as "a heroic man, a brave fighter, a night-guard". According to Ibn al-Balkhi, the rank was immediately below . In , the title is ranked below . In early Islamic period, the title appears together with , and a related title, , seems to belong to the leaders of the hierarchy of . According to Bosworth, s were separate from s, and were probably fighters with outstanding leadership or fighting qualities that were recruited from the latter.
Historical figures recorded as bearing this title include: