Mac Alastair is an Irish Gaelic surname, equivalent to the Scottish McAlister, meaning "son of Alistair." The name originated as a patronymic, indicating descent from a father named Alasdair, the Scottish Gaelic form of Alexander. Over time, it became fixed as a hereditary surname, losing its literal patronymic function. Etymology The name traces back through Alasdair, the Scottish Gaelic form of Alexander, which itself derives from the Greek Alexandros ("defender of men"). The element alexo means "to defend," and aner (genitive andros) means "man." The name Alexander was popularized by Alexander the Great and later spread throughout Europe, developing many regional forms. Historical Context The surname Mac Alastair emerged in Ireland, where it is the Anglicized form of the Gaelic patronymic Mac Alastair or Mac Alasdair. Its Scottish counterpart, MacAlasdair, has a documented history in the Highlands and Islands, where it was associated with various clans. The Wikipedia extract notes that the feminine forms are Nic Alastair (for unmarried women) and Bean Mhic Alastair or Mhic Alastair (for married women), reflecting traditional Gaelic naming conventions. Variants and Distribution Several Anglicized variants exist, including McAlister, MacAllister, and Alexander (as a surname). In Russia, the equivalent Aleksandrov and its feminine form Aleksandrova are common; in Norway, Alexandersen serves a similar role. The Sander surname in German is a shortened form of Alexander. These names spread through Celtic diaspora, especially to North America, Australia, and other English-speaking regions. Key Facts Meaning: Son of Alistair (defender of men) Origin: Irish Gaelic Type: Patronymic surname Usage Regions: Ireland, Scotland, and among their diasporas