- A prefix used with a woman's maiden surname
Fionnghuala fhionn Nic Aoidh
- fair-haired Fionnghuala McKay
This prefix replaces the prefix Mac found in male surnames, and triggers lenition of a following consonant. It is used by unmarried women, and by married women who have kept their maiden name. Thus Fionnghuala Nic Aoidh's father and brothers would use the surname Mac Aoidh.
- Ó (used in male names)
- bean Uí, Uí (used with a woman's married name)
- Ní (used in place of the male Ó prefix)