Why is the ninth month called September?
1905, from Irish, literally "we ourselves," from Old Irish féin "self," from PIE *swei-no-, suffixed form of root *s(w)e- (see idiom). Movement founded 1905 by Irish journalist and politician Arthur Griffith (1872-1922).
An Irish political party (in Gaelic it means “Ourselves Alone”) that has long combatted Great Britain's influence in Ireland and sought the unification of Northern Ireland with the Irish republic in the south; generally considered the political portion of the Irish Republican Army. One wing of it has engaged in terrorism.