Ó and Mac are common Gaelic language surname prefixes. Ó means “descendant of” while Mac means “son of”. Mc and O’ are the anglicised equivalents. Ua is an older spelling of Ó. Girls use Ní and Nig instead of Ó and Mac, while wives use Uí and Mhic. So for the Griffin surname from Co. Clare, men and boys use Ó Gríofa, girls Ní Ghríofa and wives Uí Ghríofa – Gh is silent. Surnames starting with Mac or Mc are common in Ireland and Scotland, for both Catholics and Protestants alike.
Surnames ending in “son” are also common in Ireland.
Another common surname suffix in Ireland is that of Gil / Kil which comes from the Gaelic word “giolla” which means “follower of”.
A common Norman prefix in Ireland is that of “Fitz” which also means “son of”.