Gaelic /ˈɡeɪlɪk/adjective 1noun 1 adjective1 •Of or relating to the Gaels, the Celtic peoples of Scotland, Ireland, and the Isle of Man, or their languages.I began to study coats of arms, visit the Web sites of portrait galleries and look up the etymology of Gaelic names. — 2012 noun1 •Ellipsis of Gaelic football.