Jackeen is a mildly pejorative term for someone from Dublin, Ireland. The Oxford English Dictionary defines it as "A contemptuous designation for a self-assertive worthless fellow," citing the earliest documented use from the year 1840.[1]
The term is derived from a nickname for John (i.e. Jack)from the Union Jack (As Dubliners were considered the most English of all the Irish) combined with the Irish diminutive suffix "-een" (meaning little) [1] (-ín in Irish) found in many Irish female names such as Roisín ("little Rose") and Maureen (Mairín, "little Mary"). Today, Jackeen is often used to describe Dublin GAA players and supporters.[2][3] The term has also been shortened to "Jack" or the plural "Jacks" by Dublin fans as a way to refer to themselves.[4][5]