The oldest known name for the island of Britain is Albion or Albiiū (Koch, 2003). It is mentioned in the Ora Maritima (line 100-108), where it describes Hiweros (Ireland) and its neighbouring island Albion (Britain). Pliny the Elder says this of Britain “Its former name was “Albion”; but at a later period, all the islands, ...were included under the name of “Britanniæ.” The inhabitants of Albion would then be known as Albiones or Albionioi (Cunliffe, 2013., Koch, 1986).

The current name for Britain and the British people comes to us from the Greek writer Pytheas. He calls the island of Britain ‘Pretannia’ and the people of the island Pretani, alternatively spelt Pritanī or Pritenī (Cunliffe, 2013 and Koch, 2003). Cunliffe (2013) suggests that Pretannia may have been the name for the cluster of islands and Albion of Britain specifically. Pritanī is likely an ethnonym meaning ‘painted ones’, ‘tattooed ones’, or ‘people of the forms’, but the possibility remains that it was a name given to them by the Gauls (Cunliffe, 2013 and Koch, 2003). Koch (2003) suggests that the ‘forms’ referred to in the name ‘people of the forms’ may refer to tattoos, or it may refer to poets, as seen in the Welsh word prydydd, who was the highest grade of bards. Alternatively, the ‘forms’ may be the La Tene metalwork they were famous for. 

Bibliography:

Avienus, Ora Maritima, verse translation for ToposText by Ralph B. Morley (1992- ), line 100-108. https://topostext.org/work/751 

Cunliffe, B., 2013. Britain begins. Oxford University Press.

Koch, J.T., 1986, January. New Thoughts on Albion, Iernē, and the Pretanic Isles (Part One). In Proceedings of the Harvard Celtic colloquium (pp. 1-28). Dept. of Celtic Languages and Literatures, Faculty of Arts and Sciences, Harvard University.

Koch, J.T., 2003. Celts, Britons and Gaels: Names, peoples and identities. TRANSACTIONS-HONOURABLE SOCIETY OF CYMMRODORION, pp.41-56.

Pliny the Elder, The Natural History, trans. John Bostock and H. T. Riley. London: Henry Bohn, 1855. Book 4.30. https://exploringcelticciv.web.unc.edu/pliny-the-elder-the-natural-history/