Ó m (genitive singular Uí, nominative plural Uí)
- Alternative form of ó (“grandson, grandchild”) used in surnames.
- Forms with the definite article are not found.
- The form Ó triggers h-prothesis of a following vowel.
- The form Uí triggers lenition of a following consonant.
- The form Uíbh triggers no mutation of a following sound.
|Note: Some of these forms may be hypothetical. Not every possible mutated form of every word actually occurs.
- "Ó" in Foclóir Gaeilge-Béarla, An Gúm, 1977, by Niall Ó Dónaill.
- “O'” in New English-Irish Dictionary by Foras na Gaeilge.