Fr. Matthew Kelly’s book, Calendar of Irish Saints, has an interesting example of the Irish habit of using Anglicized or Roman-calendar-ized versions of local names as baptismal names, particularly in the 1700’s and 1800’s:
“….the Christian name Moses, not uncommon in a few Eastern counties [of Ireland] is none other than Aidan or Aedh, patron of Ferns [in County Wexford], which by an ordinary custom of the Irish became Moedhog or Mogue… Moses being substituted in its place.”
As Kelly explains, it was normal to express affection for a saint by either adding a possessive prefix (“mo,” meaning “my” or “do,” meaning “thy”, like “your man Patrick”), or a diminutive suffix (“og,” meaning “young” or just a noun spinning out, as well as “in” meaning “little”, or “an” which is just a noun thing). Some saints got added stuff on both sides.
So “mo” + “Aedh” + “og” turns into “Moedhog” — which through the magic of Irish elision and vowels, is pronounced “Mogue.”
But with the new Trent regulations on baptismal names, the young Catholic priests weren’t sure what was going on with a non-Roman calendar saint like St. Aedh. So the baby Moedhogs of the area suddenly got baptized as “Moses.” (Which of course is a perfectly good name, but rather startling to have show up all of a sudden in great numbers, in southeast Ireland.)