Gaelicisation, or Gaelicization, is the act or process of making something Gaelic or gaining characteristics of the Gaels, a sub-branch of Celticisation. The Gaels are an ethno-linguistic group, traditionally viewed as having spread from Ireland to Scotland and the Isle of Man.
Gaelic, as a linguistic term, refers to the Gaelic languages but can also refer to the transmission of any other Gaelic cultural feature such as social norms and customs, music and sport.
Norman Irish or Hiberno-Normans (Irish: Normánach; Old Irish: Gall 'foreigners') is a modern term for the descendants of Norman settlers who arrived during the Anglo-Norman invasion of Ireland in the 12th century. Most came from England and Wales. They are distinguished from the native Gaelic Irish, although some Normans eventually became Gaelicised. The Hiberno-Normans were a feudal aristocracy and merchant oligarchy which controlled the Lordship of Ireland. The Hiberno-Normans were associated with the Gregorian Reform of the Catholic Church in Ireland and contributed to the emergence of a Hiberno-English dialect.
Some of the most prominent Hiberno-Norman families were the Burkes (de Burghs), Butlers, and FitzGeralds. One of the most common Irish surnames, Walsh, derives from Welsh Normans who arrived in Ireland as part of this group. Some Norman families were said to have become "more Irish than the Irish themselves" by merging culturally and intermarrying with the Gaels.