O’Donovan is probably correct when he states that this place-name is of English origin (19). Certainly there is nothing in the evidence to indicate an Irish precursor.

Examples such as ‘Earthtown’ (2), etc., are perhaps best viewed as secondary forms, likely due to the influence of the far more common ending -town. The H- in the earliest attestation ‘Herdon’ (1) is absent from all other examples and is probably prosthetic. The final -s first seen in ‘Eardownes’ (12) is clearly a plural marker in reference to the subdivisions Great and Little (4).

The original name appears to have been similar to the modern form Eardowne, but its provenance is obscure. There is no reason to believe that the final element is a reflex of Irish dún “fort”, as the English word down “hill” is known to have occurred elsewhere in the toponymy of South Wexford; it is found, for example, in the now-defunct place-name ‘Downmead [par. Drinagh]’ “hill-meadow” (see CGn. 61.352.41592). The initial element may be derived from Middle English eard “land, dwelling” (see Stratmann p.184, also EPNE i p.144; cf. OE erð ‘ploughed land’, EPNE i p.158).

As the etymology of this place-name is uncertain a translation is not possible. The Irish form of the name used here is the phonetic approximation Iardún Mór/Beag, although Éardún as suggested in BPP (p.51) is also quite acceptable.

[Derivation of the initial element from Old Norse eyrr as recently suggested ([details to be added]) is problematic. In nearby Carnsore and Greenore this element has been realised as -ore (see Mac Giolla Easpaig, D., ‘L’Influence Scandinave sur la Toponymie Irlandais’, in L’Héritage Maritime des Vikings en Europe de l’Ouest, 441‒82, ed. Ridel, É (2002). Caen.), which is inconsistent with the evidence for Eardowns. It has also been suggested that the final element may be from the Old Irish word dumach “sand-bank” ([details to be added]) (dumhach in Modern Irish), but this word is normally anglicised as doagh or similar, which not reflected in any of the evidence for this place-name. Moreover, soil maps of the townland do not reflect the presence of sand-banks or the like (see https://gis.epa.ie/EPAMaps/).]

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