Translation according to P. W. Joyce:
Gortnahown in Cork and Galway ; Gort-na-habhann, of the river : h prefixed (p. 4, X). See Au.
X. H is prefixed to a fem. noun beginning with a vowel, when that noun is in the gen. singular preceded by na, the article. Baurnahulla in Cork, anglicised from Barr-na-hulaidh [-hully], the hill-top of the uladh or altar-tomb, which in the name of the uladh or altar-tomb, which in the name appears as hulla, not ulla. See vol. i. p. 338.