British Isles (geographic)
   Great Britain
     England
     Scotland
     Wales

Ireland (geographic)
   Republic of Ireland (26 counties)
   Northern Ireland (6 counties)
United Kingdom
   Great Britain (England, Scotland and Wales)
   Northern Ireland
Ulster
   post-1922 6 counties Northern Ireland 
   pre-1922 6 counties plus Donegal, Monaghan and Cavan

Celtic languages
   Gaelic
     Irish
     Scottish
     Manx (now dead)
   Brethonic
     Welsh
     Breton
     Cornish (now dead)