Sept and Clan ?

     (The terms clan and sept have often been confused.)

CLAN-NAMES:

  Besides personal names, our Irish ancestors had from an early period, and even from pre-historic times, a complete system of fixed clan names by which each family group and its subdivisions had its own distinct name.  These clan names are of great importance in tracing the early history of families.  Though long obsolete as people-names, they still survive in many instances as baronial and parochial designations, in the same way as Norfolk and Suffolk, which were originally people-names - north-folk and south-folk - became the names of two English counties.  They were generally formed by prefixing certian words to the genitive case of the names of distinguished ancestors, sometimes gods and goddesses, or by the addition of terminations, and in many respects resemble the family names of a later period.  Some, however, and probably the very oldest, appear to be plural names, like the names of the Celtic tribes of Gaul in Caesar's time; while others are formed by prefixing certain words to place-names.

  Of words prefixed to the names of ancestors to form clan-names, we have the following:

  Cineal (Cinel, Cenel, angl. Kinel), kindred, race, descendants, as Cineal Eoghain, race of Eoghan, Cineal Conaill, race of Conall;
  Clann, children, race, descendants, as Clann Cholmain, race of Colman;
  Corca, race, progeny, as Corca Bhaiscinn, race of Baiscinn, Corca Dhuibhne, race of Duibhne;
  Dal, tribe, progeny, as Dál gCais, race of Cas, whence "Dalcassian";
  Muintear, family, people, as Muintear Mhaolmordha, family of Maolmordha, Muintear Mhurehadha, family of Murchadh;
  Siol, seed, progeny, as Síol nAnmchadha, seed of Anmchadh, Síol Muireadhaigh, seed of Muireadhach;
  Sliocht, progeny, as Sliocht Aodha Sláine, progeny of Aodh Sláine;
  Teallach, family, household, as Teallach Dhunchadha, household of Dunchadh;
  Ui, grandsons, descendants, as Uí Breasail, descendants of Breasal, Uí Liatháin, descendants of Liathán, Uí Néill, descendants of Niall.

  Of terminations used to form clan-names, we have the following:

  -acht, as in Cianacht, race of Cian, Eoghanacht, race of Eoghan;
  -na, as in Dealbhna, race of Dealbhaoth;
  -ne, as in Conmhaicne, race of Conmhac;
  -raighe, as in Caonraighe, Calraighe, Muscraighe, &c.

  Of words prefixed to place-names, we have the following:

  Aes, people, as Aes Aisde, Aes Gréine, Aes-trí-máighe;
  Feara, Fir, men, as Feara Luirg, men of Lurg, Fir Teathbha, men of Teffia;
  Pobol, people, as Pobul Uí Chaoimh, O'Keeffe's people, Pobul Uí Cheallacháin, O'Callaghan's people;
  Tuath, people, clan, state, as Tuath Luimnigh, people of Luimneach.

  Some, if not all, of these ancient clan-names were capable of being turned into personal surnames by prefixing Moccu, later Mac U, to the genitive case of the eponym.  Thus St. Molua, who belonged to Corca Oiche, is in the annals of Ulster twice called Lugaid Mac U Ochae, that is, Lughaidh, son of the descendants of Ochae (Fochae, the ancestor of the Corca Oiche).  Hence probably such modern forms as Mac Ui Caoim, Mac Ui Oriain, for persons surnamed O'Keeffe and O'Brien respectively (see page 22).

  These ancient clan-names in many instances differ little, if at all, in fomr from modern family nmes.  Muintear and Clann which occur so frequently in clan-names are also used to form the collective plural of family names, as Muintear Loinsris, the O'Lynches, Clann tsitis, the MacSheehys, or Sheehys.  (see p.25.)  Similarly Uí, of frequent occurrence in clan-names, is also the plural of Ua of family names.  Hence very often the same form, or nearly the same, is a clan-name and family name, but the meaning in each case is entirely different.  Muintear Ifeapnain, for instance, as a family name denotes the O'Heffernans of Owney, but as a clan-name the O'Quins of Thomond.  Irish writers have been frequently led into error by this similarity or identity in form of names of widely different meaning.

  Only such clan-names as are mentioned in the preceding notes are here explained, and they are taken in their original sense of people-names.

From the book: 'Surnames of Ireland, Or Sloinnte Gaelheal Ls Gall' by Rev Patrick Woulfe, page 685-691

    The term "sept" has never, as far as can determine, been given an authoritative technical definition.  It can perhaps best be explained by saying that it is a collective term describing a group of persons who, or whose immediate and known ancestors, bore a common surname and inhabited the same locality.

Source:  Edward MacLysaght, Irish Families, Dublin: 1991, page 12 (Introduction). 

    As defined above by Edward MacLysaght, The Dalcassian Clan would be a better label comprised of 118 septs, as listed on the Dalcassian Clan webpage.   An example would be the O'Brien Sept as part of the Dalcassian Clan.  By the same token, O'Brien is also a Clan with 8 septs descended from them.  As such, all Dalcassian families are septs and part of the Dalcassian Clan.  Some septs are also clans as they have septs who descend from them.  Durkin, Eustace, Haly, Hickey, MacNamara, O'Brien, O'Dea, O'Hanrahan, O'Heffernan, O'Kennedy, O'Neill, O'Seasnain, Muldowney, Quinn and Shannon could be considered as either a Clan and a Sept depending on construction.

     Ireland was one of the earliest countries to evolve a system of hereditary surnames. They came into being fairly generally in the eleventh century, though some were formed as early as the year 1000. Brian Boru, high king of Ireland, who died at the Battle of Clontarf in 1014, is often erroneously credited with decreeing that the use of surnames should become a requirement among his subjects.  In fact the system developed spontaneously in Ireland, as it did elsewhere, as a result of the need for personal identification in an increasing population.