Definition of "Fenian"

(British, Ireland) An Irish nationalist or republican.  examples

(historical) A member of the Fenian Brotherhood or the Irish Republican Brotherhood, Irish republican organizations active in the nineteenth and early twentieth centuries.

(derogatory, Scotland and Northern Ireland) A Catholic, especially one of Irish ethnicity or descent.  examples

(derogatory, Scotland and Northern Ireland) A supporter of Scottish association football club Celtic F.C.  examples