The term Irish Celts, Language of is answered by the crossword solution GAELIC (6 letters). GAELIC is an Indo-European language spoken in Ireland and Scotland. It is the native language of the Irish and Scottish people and is also known as Irish GAELIC or Erse. GAELIC is a Celtic language and is closely related to Manx and Welsh. It is an official language of the European Union and is used in many parts of the world.