Where a particular surname abounded in a particular district it was necessary to attach a sobriquet to the surname to distinguish one family from another.
Much in the same way as surnames, these sobriquets comprise personal characteristics, place from whence, the name of an ancestor etc.
In some localities, the people had a penchant for bestowing personal nicknames, necessary or not.
Found in the Kenmare Manuscripts c 1725 are Teige a Gaddee (Tadhg an Gada∅, T. the thief), Daniel na Geragh (D≤nal na gCaorach, D of the Sheep), John na Guppoge: Sean na gCup≤g, S of the Dock Leaves) etc.
Teige mar Sude, also found in the Manuscripts, suggests that this Tadhg may have been in the habit of saying mar si·d Θ , "so it is/such is the way".
Samples found in The Irish Fiants of the Tudor Sovereigns (1522-1603) are Rerie m'Philip I Kellie alias Gruogagh Galtigh, and John m'Donell I Reile alias Bolugedany (? Bolgadβna∅ bolgadβn, a corpulent person).
The latter is found in a 1601 pardon with James Butler, brother of the lord baron of Cahir (Co Tipperary) and it is probable that he may have borne the surname (O) Ryle.
Seβn de Bhulbh's Sloinnte na h╔ireann/Irish Surnames gives this as ╙ Raghaill, the derivation of which is not clear. However, MacLysaght's The Surnames of Ireland says its equation with the Kerry Rahilly would seem possible.
Rahilly derived from ╙ Rathaile, is a name long associated with Co Kerry though originally a branch of Cineβl Eoghain in Ulster.
This is not to be confused with the Co Cavan surname ╙ Raghallaigh, which was anglicised to (O) Reilly.
The O Rahillys had reached Munster by the 14th century, as noted by The Justiciary Rolls (1308-1314). At a hearing in Cork in 1311 a man was charged with receiving William Duff Crayghly and his son, named as incendiaries and common robbers, who, with another, robbed David le White of Ballysallagh (Co Cork parish of either Hackmys, Lisgoold or Rathgoggan).
That same year John Crayghly was among the notables of Cork city admitted to make fines etc, for all trespasses and felonies committed by them.
In 1577 Deremot O Rahilly m'Dermod, Carrignamuck, was among the pardoned as listed in The Irish Fiants of the Tudor Sovereigns (1522-1603), as was John m'Morice O Rahelly of Cromae the following year.
Carrignamuck names townlands in the Co Cork parishes of Macroom and Dunmanway. In 1601, persons so-named were among the pardoned, from Ballyvirrane (parish of Kilcolman, Co Kerry), Rathcannon (Co Limerick parish of Athlacca), and Drominagh (? Co Cork parish of Dromtarriff).
Shane and Donell O Rahillie were among hundreds of pardoned persons in Co Cork.
O Realy is listed in A Census of Ireland circa 1659 among the principal Irish names in the Co Cork barony of Kinalmeaky, as was Rely in Kilkenny city and county.
Seven of the eight bearing this surname in the Kenmare Manuscripts (1620-1788), had addresses at Kilquane, Killarney's Hen Street, Moyeightragh, Anaghcuilymore, and Allaghcommon.
The only one to still retain the "O" was poet Egan O Rahilly, Aogβn ╙ Rathaile (1670-1726). Aogβn was born at Scrahanaveal (Screathan an Mh∅l) in the Co Kerry parish of Kilcummin.
Screathan is "a scree, a stony slope", and the final element appears to be m∅ol, "a beast or animal, an insect". M∅ol m≤r is a whale, m∅ol goile, an intestinal worm, with numerous varieties of m∅ol in between.
John Rahilly, Kenturk, with 174 Co Cork acres, was the only person bearing that surname found in the 1876 Owners of Lane of One Acre and Upwards.
There are 30 Rahilly telephone entries, mainly in the west Munster area, and 56 O Rahilly entries, 25 of which are in the same locality. There are none in the original Irish, but two rendered O Rahelly.
Ua Duinn∅n's Focl≤ir Gaedhilge agus BΘarla informs that ╙ "is often applied independently to the clan-chief, eg ╙ Rathaile, the O Rahilly; ╙ NΘill, the O Neill; ╙ Conchubhair Donn, the O Connor Don".
Kerry-born Michael Joseph O'Rahilly (1867-1916) nationalist and journalist, who was involved in the founding of the Irish Volunteers and who was shot during the Easter Rising 1916 , was commonly known as "The O Rahilly".
His son Aodhagβn surmised the use of the title "Ua Rathghaile" or "The O Rahilly" was first used by him merely as a pen-name, and that it continued in use after 1914.
And if his title was assumed, his uaisleacht could be claimed from the fact that he was a direct descendant of poet Aogβn O Rathaile.