The evidence for this anglicised place-name does not support derivation from O’Donovan’s suggested ‘Garthaidh an chaca’ [Garraí an Chaca] (6), as there is no unambiguous evidence to suggest either the initial ch- or final -a of hypothesised gen. sg. chaca (cf. Tattincake/Táite an Chaca, MN; Monacocka/Móin an Chaca, TY; Mullinahack/Muileann an Chaca, D; see logainm.ie).

The historical forms instead suggest straightforward derivation from Garraí Hac “Hack’s enclosure, garden”. It has been noted above that the element hack as found in BALLYHACKBEG (#53590) (par. Tintern) and BALLYHACK (#53342) (par. St. James & Dunbrody) is most likely from Hack, an English surname (ultimately of Norse origin) brought to Ireland with the Anglo-Normans. The Irish form used here, Garraí Hac, is consistent with attestations of this surname in Irish texts, e.g. ‘Hac’ and ‘Shac’ (see BALLYHACK, par. St. James & Dunbrody; cf. BPP p.54).

This name is a very rare example of the occurrence of an element borrowed from the Anglo-Normans in an Irish place-name in the barony of Forth. The handful of toponyms of this type in South Wexford indicate that despite intensive colonisation there were areas in Forth and Bargy where the Irish language remained sufficiently vibrant to generate Irish place-names after the Anglo-Norman invasion (see Introduction).

Garraí may refer to the interior of the enclosure located in this townland (see archaeology.ie; see GARNAKILL (#52863), par. Killenagh; GARRYGIBBON (#53688), par. Ardcolm).

[Derivation of the initial element from Old Norse gerði, as recently suggested ([details to be added]), is problematic. Old Norse gerði was gaelicised as gearraidh with palatal initial g- (see Henderson, The Norse Influence on Gaelic Scotland, p.164), a word which is not reflected in any of the evidence for Garryhack. The element garry found in anglicised place-names in Ireland usually reflects garraí, a borrowing from another Old Norse word, garðr, via Old Irish garrda (see dil.ie). This is the most reasonable derivation in this case. The borrowed element garraí became exceedingly productive in Irish and is found in place-names throughout the country, particularly in the southern half (see logainm.ie). We find numerous place-names such as GARRYRICHARD/Garraí Risteaird (#53509) (par. Clongeen) and GARRYWILLIAM/Garraí Liam (#53715) (par. Kilpatrick), examples of garraí in Irish place-names which self-evidently date to some point after the Anglo-Norman invasion, as they contain a personal name borrowed from that invading group. In the present place-name, given that Hack is well-attested among the Anglo-Normans in England as a surname and personal name, albeit ultimately of Norse origin (see The Oxford Dictionary of Family Names in Britain and Ireland, eds. Patrick Hanks, Richard Coates, and Peter McClure, 2016; see also Townland Names of County Wexford s.n. BALLYHACK), it is more than possible that Garryhack is another example of Irish ‘garraí + AN name/surname’ coined after the Anglo-Norman invasion.

In short, owing to the etymology of Irish garraí and Anglo-Norman Hack, Norse derivation cannot be completely ruled out on linguistic grounds, but in the absence of unambiguous pre–Anglo-Norman evidence it would clearly be methodologically unsound to infer Scandinavian settlement from these two elements.]

[Excerpt from Logainmneacha na hÉireann IV: Townland Names of County Wexford, 2016, with additional material in square brackets [ ].]