The final element in this place-name is quite opaque. The sound represented by the first letter of -gerry, pronounced /ʤ/ as in John (see 20, 22, 25) is not common in Irish. The sixteenth-century spelling in -ch- (3) occurring alongside forms in -g- (1–2, 4–17) appears to indicate that this /ʤ/ was also the pronunciation prior to the nineteenth century. But it is difficult to determine what the initial of that word may have been in the original Irish precursor.

O’Donovan’s suggestion that the place-name may derive from ‘Ballydermot’ (24) is no doubt based on the fact that the Irish personal name Diarmaid was frequently anglicised using the unconnected biblical name Jeremiah (see Ó Corráin & Maguire, 1981 pp.73–4). However, this derivation can be completely discounted as is not reflected in any of the historical evidence here. Nevertheless, it is true that palatal (slender) d- in Irish names was often realised as /ʤ/ in anglicised forms, and it is possible that the initial of the final element of -gerry could have derived from an Irish word beginning in d-. The personal name OIr. Demre [ˈdʹevʹrʹe] would have developed to Deimhre [ˈdʹiːrʹə] in many dialects of Modern Irish (cf. OIr. gemred > Mod.Ir. geimhreadh “winter”). This name is found in the genealogies of two of the Fotharta population groups from whom the barony of Forth, in which this townland is located, derives its name (see CGH 126a29; 337h43).

That said, there is not enough evidence to corroborate this hypothesis, and given that no obvious alternative presents itself, the precursor seems best represented here by the phonetic approximation Baile Déire.

[It has recently been suggested that the final element of this place-name is from Old Norse gerði ([details to be added]). However, this suggestion is particularly problematic given the fact that ON gerði was realised as gearraidh in Gaelic (Henderson, The Norse Influence on Gaelic Scotland, p.164)—this gearraidh would not be expected to generate an anglicised form as reflected in the overall evidence for this place-name, as it has neither the initial /ʤ/ nor the long penultimate vowel found in the local pronunciation of Ballygerry, namely [ˈʤeːriː]. In this regard it is worth comparing the Gaelic place-name Taigh a’ Ghearraidh on South Uist in the Hebrides which has been anglicised as Tigharry. This suggested derivation is therefore highly unlikely to be correct.]

[Excerpt from Logainmneacha na hÉireann IV: Townland Names of County Wexford, 2016]