Epithets

A first name may be modified by an adjective to distinguish its bearer from other people with the same name. Mór (“big”) and Óg (“young”) are used to distinguish father and son, like English “senior” and “junior“, but are placed between the given name and the surname: Seán Óg Ó Súilleabháin corresponds to “John O’Sullivan Jr.” (although anglicized versions of the name often drop the “O’” from the name).

The word Beag/Beg, meaning “little”, can be used in place of Óg. This did not necessarily indicate that the younger person was small in stature, merely younger than his father. Sometimes beag would be used to imply a baby was small at birth, possibly premature.

Adjectives denoting hair color may also be used, especially informally: Pádraig Rua (“red-haired Patrick”), Máire Bhán (“fair-haired Mary”).

Surnames and prefixes

A male’s surname generally takes the form Ó/Ua (meaning “descendant”) or Mac (“son”) followed by the genitive case of a name, as in Ó Dónaill (“descendant of Dónall”) or Mac Lochlainn (“son of Lochlann”).

A son has the same surname as his father. A female’s surname replaces Ó with Ní (reduced from Iníon Uí – “daughter of a descendant of”) and Mac with Nic (reduced from Iníon Mhic – “daughter of the son of”); in both cases the following name undergoes lenition. However, if the second part of the surname begins with the letter C or G, it is not lenited after Nic. Thus the daughter of a man named Ó Dónaill has the surname Ní Dhónaill; the daughter of a man named Mac Lochlainn has the surname Nic Lochlainn. When anglicized, the name can remain O’ or Mac, regardless of gender.

If a woman marries, she may choose to take her husband’s surname. In this case, Ó is replaced by Bean Uí (“wife of a descendant of”) and Mac is replaced by Bean Mhic (“wife of the son of”). In both cases, the bean may be omitted, in which case the woman uses simply Uí or Mhic. Again, the second part of the surname is lenited (unless it begins with C or “G”, in which case it is only lenited after Uí). Thus a woman marrying a man named Ó Dónaill may choose to use Bean Uí Dhónaill (Mrs. O’Donnell in English) or Uí Dhónaill as her surname; a woman marrying a man named Mac Lochlainn may choose to use Bean Mhic Lochlainn (Mrs. McLaughlin in English) or Mhic Lochlainn as her surname.

If the second part of the surname begins with a vowel, the form Ó attaches an h to it, as in Ó hUiginn (O’Higgins) or Ó hAodha (Hughes). The other forms affect no change: Ní Uiginn, (Bean) Uí Uiginn; Mac Aodha, Nic Aodha, Mhic Aodha, and so forth.

Mag is often used instead of Mac before a vowel or (sometimes) the silent fh. The single female form of “Mag” is “Nig”. Ua is an alternative form of Ó.

Some names of Norman origin have the prefix Fitz, from Latin language filius “son”, such as Fitzwilliam, Fitzgerald, and so forth. Other Norman surnames may have the prefix “de”, such as de Búrca, de Paor, or de Róiste. – cont’d…