1A Gaelic form or version of a word or name; an adaptation into Gaelic.
2The adoption of Gaelic language or culture; the process of becoming Gaelic-speaking.
Usually with reference either to the assimilation of the descendants of Anglo-Norman settlers in Ireland in the Middle Ages, or to the promotion and revival of Irish culture and language in Ireland in the late 19th and 20th centuries.
Early 20th century; earliest use found in Gaelic Journal. From Gaelicize + -ation.