This poorly-attested place-name appears to be a late English creation. The same name is found in North Wexford, where it also seems to be a relatively recent English formation (see RACECOURSE [#53234], par. Kilnahue).

Racecourse occurs as a townland name in counties Dublin, Galway, Tipperary and Waterford (see logainm.ie). The Irish form of the name recommended here uses the standard translation An Ráschúrsa (see FGB, tearma.ie). Racecourse in Waterford was gaelicised locally as Cúrsa an Ráis. In Ballyhoge (par.) we find the obsolete minor name, ‘Birch Grove ows. King’s Quarter ... commonly known by the name the Race Course’ (CGn. 726.456.495991), and in Inch (par., bar. Gorey) a portion of the lands of GORTEEN was once known as ‘race cource [sic]’ (CGn. 511.270.331611).

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