Scoti or Scotti was the generic name used by the Romans to describe those who sailed from Ireland to conduct raids on Roman Britain. It was thus synonymous with the modern term Gaels. The earliest instance of the term Scot(t)i occurs in the appendix to the Laterculus Veronensis, dated to c.314. Previously Latin authors designated the inhabitants of Ireland as Hiberni. Thereafter, periodic raids by Scot(t)i are reported by several later fourth-/early fifth-century Latin authors, namely Pacatus, Ammianus Marcellinus, Claudian and the Chronica Gallica of 452. Two references to Scot(t)i 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 Irish raiding from the early 360s, culminating in the so-called "barbarian conspiracy" of 367-8, and continuing, if episodic hostilities up to and beyond the end of direct Roman rule c.410. The location and frequency of attacks by Scotti remain uncertain, as do the origin and identity of the Irish population-groups who participated in these raids. In the fifth century, some of these raiders established the kingdom of Dál Riata, outside the former Roman province, along the west coast of Scotland. As this kingdom expanded 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 Scot(t)ti is obscure. It is not a Latin derivation, nor does it correspond to any known Goidelic term the Irish used to denominate 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 acquired the sense of an ethnonym. Several derivations have been conjectured but none has attained general acceptance in mainstream scholarship. In the nineteenth century Aonghas MacCoinnich proposed that Scot(t)ti was derived from Gaelic Sgaothaich, "crowd". 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 signified a band of outcast raiders. More recently, Freeman has speculated on the possibility of a group of raiders adopting a designation derived from an Indo-European root *skot, citing the parallel in Greek skotos (σκότος), meaning "darkness, gloom".
Scotland takes its name from Scotus which in Latin translates into Irishman (masculine form of Scoti). This is in reference to the Gaelic settlers from Ireland which was named Scotia (feminine form of Scoti) during this Epoch. The settlers from Ireland in nowadays Scotland were known as Scoti.