Oxford Dictionary of Modern Slang (edited by John Ayto, John Simpson) lists the following slang words used for Irish people:
bog-trotter, harp, Mick, Paddy, Pat, turk, turkey
I can guess why these terms are associated with Irish people except turk and turkey. (bog-trotter can be analyzed further though.)
- bog-trotter: because there are many bogs in Ireland
- harp: symbol of Ireland, popular instrument in Ireland
- Mick, Paddy, Pat: (derived from) popular names in Ireland
- turk, turkey: [seriously?]
On the other hand, the racial slur database doesn't include turk and turkey among many slang words.
I did some research and found an article on word-detective.com that explains possible origins. First theory is related to the stupidity of turkey bird, second theory is related to the uncivilized behavior of a person ("Turk" from US slang) and third theory is related to the derivation of the Irish word "torc".
As to why an Irish-born person resident in another country would be known as a "turkey" or "turkey bird," the crystal ball gets a bit cloudy. This term seems to be largely heard in the US, where "turkey" has long been slang, in reference to the bird's legendary stupidity, for something (or someone) of little value, so there's a possibility that it is simply another derogatory sense of this slang "turkey."
More likely, however, is the possibility that "turkey" in this sense is a development of "Turk," a native of Turkey, which has long been used in a derogatory slang sense in many contexts to mean a person lacking "civilized" qualities. "Turk" has been used in the US as slang for a person of Irish birth or descent since at least 1914, while the form "turkey" in the same sense is first found in the 1930s.
Yet another possibility, bypassing Turkey entirely, is that "turk" and "turkey" in this sense is derived from the Irish word "torc," meaning "hog or boar."
Furthermore, there is a new study claims that Irishmen descended from Turkish farmers which might be related:
A new study has revealed that many Irish men may be able to trace their roots back to Turkey. Focusing on the role of the Y chromosome, which is passed from father to son, the research indicates Turkish farmers arrived in Ireland about 6,000 years ago, bringing agriculture with them. And they may have been more attractive than the hunter-gatherers whom they replaced. [irishcentral.com]
In the light of the those findings, is it possible to trace back this usage to find a more definitive answer?
Best Answer
'Turk' in reference books
J.S. Farmer & W.E. Henley, Slang and Its Analogues (1904) has a fairly lengthy entry for turk:
Perhaps the most interesting thing about this entry—aside from its mention of the usage of "young Turk" just four years before the Young Turk Revolution in Turkey—is its silence with regard to any connection between turk and Irish Americans.
Also free of any reference to Irish people is Joseph Wright, The English Dialect Dictionary (1905):
Harold Wentworth & Stuart Flexner, Dictionary of American Slang (1960), however, does note the association of turk with people of Irish ethnicity:
On the other hand, Eric Partridge, A Dictionary of Slang and Unconventional English, fifth edition (1961) asserts that turks in connection with the Irish is a feature of (fairly recent) Teddy boy slang:
Three pitchers named Turk
When I was young, one of the stars of my home-town baseball team, the Houston Colt .45s, was a right-handed starting pitcher from Boston named Dick Farrell, who was known as a fun-loving, hard-partying person, but with a somewhat hot temper. His nickname was Turk—and according to an article about him posted on the Society for American Baseball Research website, his father was known as Big Turk. I don't know whether the father's Irish ethnicity had anything to do with that nickname, but he may have been Big Turk by the 1930s (Dick Farrell was born in 1934).
Aside from that rather tenuous connection, I have never heard an Irish or Irish-American person referred to as "Turk" or "a turk," and the usage may be obsolete or nearly so in the United States. Another pitcher, though from a generation later, Turk Wendell (born in Pittsfield, Massachusetts in 1967), is said (in his SABR biography) to have acquired his nickname as follows:
A third baseball pitcher, Turk Lown, who was born in Brooklyn, New York, in 1924, "got his nickname as a child because of his fondness for eating turkey," according to a Wikipedia article about him. Neither Wendell nor Lown is an Irish surname.
The most likely sources for the term turk as applied to an Irish or Irish-American person, I think, are Turk (a native of Turkey) as a byword for someone savage (an expression of bigotry that was probably several centuries in the making), and torc (the intemperate and unmanageable Gaelic wild boar). I seriously doubt that turkey (the North American bird) has anything to do with the usage.
UPDATE (2/3/2017): Early newspaper mentions of 'Irish Turks'
The earliest instance that I've been able to find of Turk as a direct insult term (that is, as a fighting word) for an Irish person is from "Can He Be Trusted with a Club: Policeman McCullough Gets into a Quarrel with Two Women," in the [New York] Sun (July 2, 1888):
This story is interesting, in part, because the surnames of those mentioned suggest that everyone involved may have been of Irish descent.
More-ambiguous instances of "Irish Turk" in newspaper accounts go back to the 1840s. From "City Intelligence," in the New York Herald (June 9, 1842):
Here it appears that Turk is being used as a slang term for "bigamist" and that Irish Turk is simply a juxtaposition of the defendant's ethnicity with his presumed marital status. But "Irish Turk" appears in a somewhat similar context 22 years later. From "Broadway Below the Sidewalk," in the New York Clipper (April 23, 1864):
Other nineteenth-century instances involve music-hall entertainments that seemingly focus on Irish characters. From an advertisement in the New York Clipper (September 10, 1881):
From "Thespian Temples," in the Leadville [Colorado] Daily Herald (January 8, 1882):
From an advertisement for the Alhambra Music Hall, in the Sydney [New South Wales] Morning Herald (August 20, 1888):
Delowery, Graydon, and Holland continued to perform this act for more than a decade, as we see from an advertisement in the Perth Western Australian from February 12, 1898, promoting "DELOHERY. CRAYDON, and HOLLANE In one of their funniest and best Irish character sketches, 'Irish Turks.'"
Conclusions
The association of "Turk" with Irish people goes back well into the nineteenth century—with "big Irish Turk" unmistakably intended as an insult in an incident reported in 1888. The very early occurrences (from 1842 and 1864) of "Irish Turk" in connection with a person who has multiple wives is intriguing, but not unmistakably a set phrase. Instances of "Irish Turks" as stock characters in popular entertainments occur in both the United States and Australia by 1888.