Root form: Siacas
Irish-language surnames
Mac Siacais, Mhic Shiacais, Nic Shiacais
Male form
- Nominative
- Seán Mac Siacais
- Genitive
- Sheáin Mhic Shiacais
- Vocative
- a Sheáin Mhic Shiacais
Wife form
- Nominative
- Síle Mhic Shiacais
- Genitive
- Shíle Mhic Shiacais
- Vocative
- a Shíle Mhic Shiacais
Daughter form
- Nominative
- Síle Nic Shiacais
- Genitive
- Shíle Nic Shiacais
- Vocative
- a Shíle Nic Shiacais
English-language surnames
- Jackson