The name Pict

Picti (Latin), is first used by Eutropius in 297 CE in a panegyric on Constantius Caesar, at which date the Picts become a historical people. Earlier Latin authors used the term Caledoni for the inhabitants of the region north of the Antonine Wall where we later find the Picts.

Later Latin writers produced an etymology based on the Latin word for painted. This coupled with the remark made by J Caesar, some three hundred years before the emergence of the Picts, on the British practise of painting their fighting men with Woad, has led to a great deal of confusion. We do not know what the Picts called themselves.

In Old Norse they are Péttar, Péttir or Peti. In Old English they are called Pehtas, Pihtas, Pyhtas, Piohtas or Peohtas. Old Norse also records the Petlandsfjorthr, the Pentland Firth. An original form with ht would have mutated to tt around 700 CE giving the earliest date for the use of the name in Old Norse. Old English retained the old form because the fricative h persisted in that language until the fourteenth century. A form Pect among the Picts could have been borrowed into Old English as early as 450 CE, substituting the English ht for ct as in the loan word truht from Latin tructa "trout".
The Irish (Scots) used the name Cruithni (Gaelic) which is supposed to mean "the picture people" and to refer to body paint or tattooing. There is no evidence for this and the term could have arisen equally well from the Pictish Symbol Stones.

The evidence of place-names

Place-name studies contribute the generic element Pett used exclusively in the eastern part of the area presumed to be that of the Picts. The word occurs in Welsh as peth, Cornish as peth "thing", Breton as pez "piece", and Gaelic cuid, but not in place-names. Low Latin has petia terrae for a piece of land where petia is presumed to be a loan word from a Gaulish *petia. In France, Poitou and Poitiers derive from the Gaulish tribal name Pictavi that contains the same element.

Pett, modern Pit, occurs in some three hundred place-names as a first element combined with a Gaelic or, very rarely, a Cumbric specific element. The historical Picts then, could not have coined the names with Gaelic elements. They must have been created in a bilingual situation where the Pictish term Pett for 'share' or 'portion' of land was understood by Gaelic speakers. These circumstances could have arisen in the late ninth century.