The inhabitants of ancient Ireland were initially known by a single name. However, as the population grew this was not definitive enough to distinguish between similarly named persons. According to the scholar of Irish surnames Edward MacLysaght (1887–1986), 11th-century Ireland was one of the first countries to develop a system of hereditary surnames.
The names were created in the ancient language of Ireland, also known as Gaelic. Early Irish surnames were formed by prefixing or to the first name of the father or grandfather or earlier ancestor being the Irish for ‘son’ and or being the (from ‘daughter of’) or Nic (from ‘daughter of the son of’), but the female form did not make its way into the lexicon of Irish surnames and is only used by Irish speakers.
