Labhrás wrote:
Clann doesn’t actually mean "
clan" in Irish.
You won’t find "clan" in the major Irish-English dictionary:
https://www.teanglann.ie/en/fgb/clanClann means children, offspring.
Nevertheless it is used in names of some clans/septs/tribes/families (besides cineal, dál, corca, síol, Uí etc.)
But the Decies are simply "na Déise" or "na Déisigh" without any such noun, as far as I know (which isn’t very far in this respect, I must admit

).
So: Cathal na nDéise, Cathal na nDéiseach, Cathal, fear na nDéise or similar.
Go raibh míle maith agat. Yes from what I know "na nDéise" was a name given to a tribe of people from a specific geographical location / domain / district on this island of Ériu, rather than a "Surname" that are of a specific family.
https://celt.ucc.ie/published/T302005.htmlhttps://en.wikipedia.org/wiki/The_Expulsion_of_the_Déisi
https://en.wikipedia.org/wiki/DalcassiansClaíomh Solaishttps://en.wikipedia.org/wiki/Cla%C3%ADomh_SolaisThese are the definitions I have for Clann form Foclóir Gaeilge-Béarla - Niall Ó Dónaill 1977...
Clann - 1. - Children, offspring ~ Mac, iníonachta
Clann - 2. - a Gael, the Gaels ~ a Néill, the race of Niall. (Usually in reference to Mac - surnames)
Clann - 3. - Followers
Clann - 4. - Lit: Plant
Clann - 5. - (Of hair) Lock
Clann - 6. - Weaving: Two interlocked threads on warping frame
http://www.irishidentity.com/names/d.htmDease - Déise
Deasey - Déiseach
Deasy - Mac an Déisigh (Sligeach)
From the same dictionary I get the following translations
Déiseach - a Native of the Decies
Déisigh : Déiseach
Déise : Déis
Déis : 1. Tenant, vassal 2. Rent-paying community 3. Domain, district.
Déis : Dias
Dias : 1. Ear of Corn, ear of wheat, of barley 2. Spike 3. (Of weapon) Point ~
claímh, point of sword.
Arm déise, pointed weapon. 4. (Of person) Scion
I would still like to know what if I wanted to put the word 'Clann' into my name as a Title of Gaelic distinction from the English 'Mr' Title then does it have a séimhiú?
Which of the following is most correct...
Cathal O Chlann Déiseach
Cathal O Clann Déiseach
Cathal Chlann Déiseach
Cathal Clann Déiseach
or after your generous contribution which of the following...
Cathal Chlann na nDéiseach
Cathal Clann na nDéiseach