Breandán wrote:
An Lon Dubh wrote:
The exceptions, words like "loch" you're never going to be calling to anyway!
Surely someone must have used the vocative of
loch at some stage for people to know now that it is irregular?

Oh I explained that badly!
Lughaidh already mentioned the context, but also I made it sound like the nouns were irregular, but really
they're just masculine nouns in the 3rd declension. (gentive formed via adding -a + broaden final consonant, for anybody reading, i.e. an feirmeoir, bó an feirmeora).