An early use of the word can be found in the Nomina Provinciarum Omnium (Names of All the Provinces), which dates to about AD 312. This is a short list of the names and provinces of the Roman Empire. At the end of this list is a brief list of tribes deemed to be a growing threat to the Empire, which included the Scoti. There is also a reference to the word in St Prosper's chronicle of AD 431 where he describes Pope Celestine sending St Palladius to Ireland to preach "ad Scotti in Christum" ("to the Irish who believed in Christ").
Thereafter, periodic raids by Scoti are reported by several later 4th and early 5th century Latin writers, namely Pacatus, Ammianus Marcellinus, Claudian and the Chronica Gallica of 452. Two references to Scoti have recently been identified in Greek literature (as Σκόττοι), in the works of Epiphanius, Bishop of Salamis, writing in the 370s. The fragmentary evidence suggests an intensification of Scoti raiding from the early 360s, culminating in the so-called "barbarian conspiracy" of 367–8, and continuing up to and beyond the end of Roman rule c. 410. The location and frequency of attacks by Scoti remain unclear, as do the origin and identity of the Gaelic population-groups who participated in these raids. By the 5th century, the Gaelic kingdom of Dál Riata had emerged from Ulster, overtaking parts of western Scotland. As this kingdom grew in size and influence, the name was applied to all its subjects – hence the modern terms Scot, Scottish and Scotland.
The etymology of Late Latin Scoti is unclear. It is not a Latin derivation, nor does it correspond to any known Goidelic (Gaelic) term the Gaels used to name themselves as a whole or a constituent population-group. The implication is that this Late Latin word rendered a Primitive Irish term for a social grouping, occupation or activity, and only later became an ethnonym.
Several derivations have been conjectured but none has gained general acceptance in mainstream scholarship. In the 19th century Aonghas MacCoinnich proposed that Scoti came from Gaelic Sgaothaich, meaning "crowd" or "horde". Charles Oman favoured Gaelic Scuit, with the sense of a "man cut-off" or "broken man", suggesting this was not a general word for Gaels but a band of outcast raiders.
More recently, Philip Freeman has speculated on the likelihood of a group of raiders adopting a name from an Indo-European root, *skot, citing the parallel in Greek skotos (σκότος), meaning "darkness, gloom".
An origin has also been suggested in a word related to the English scot (as in tax) and Old Norse verb sköta; this referred to an activity in ceremonies whereby ownership of land was transferred by placing a parcel of earth in the lap of a new owner, whence 11th century King Olaf, one of Sweden's first known rulers, may have been known as a scot king.
The Gaels traced their ancestry to two different mythological daughters of two different Egyptian Pharaohs named Scota.
- Philip Freeman Scotia modern Ireland and the Classical World
- Maire and Liam de Paor Early Christian Ireland
- Pacatus, Panegyric 5.1
- Amm. Marc. Res Gestae 20.1.1; 26.4.5; 27.8.5
- Claud. De III cons. Hon. 52-8; De IV cons. Hon. 24-33; De cons. Stil. 2.247-55; Epithal. 88-90; Bell. Goth. 416-18
- Chron. Gall. a. 452, Gratiani iv
- Rance (2012)
- Freeman (2001) 88-106; Rance (2012)
- The Encyclopedia Americana: A Library of Universal Knowledge: Volume 15, (1919) Encyclopedia Americana Corp., University of Wisconsin - Madison
- A. MacCoinnich, Eachdraidh na h-Alba (Glasgow, 1867)
- C. Oman, A History of England before the Norman Conquest (London 1910) 157
- Freeman (2001) 93
- Demitz in Throne of a Thousand Years p. 9
- Öknamn och tillnamn på nordiska stormän och kungligheter ISBN 91-87064-21-9 p23 (etymology of epithets of Nordic kings and magnates)
- Freeman, Philip (2001), Ireland in the Classical World (University of Texas Press: Austin, Texas. ISBN 978-0-292-72518-8
- Rance, Philip (2012), 'Epiphanius of Salamis and the Scotti: new evidence for late Roman-Irish relations', Britannia 43: 227-242