Gaelicization or Gaelicisation is the act or process of making something Gaelic, or gaining characteristics of the Gaels. The Gaels are an ethno-linguistic group who are 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, sport etc.
Examples of Gaelicisation in history include the Picts, Hiberno-Normans, Scoto-Normans and Norse-Gaels. Today, Gaelicisation, or more often re-Gaelicisation, of placenames, surnames and given names is often a deliberate effort to help prevent the further decline of the modern language.