Occasionally it instead refers to only Scotland, whose name in Gaelic is Alba (and similarly, in Irish, and Yr Alban in WelshWelsh Lexicon Forms. Cardiff University, Cardiff School of Computer Science. Retrieved 19 January 2006.). Pliny the Elder, in his Natural History (iv.xvi.102) applies it unequivocally to Great Britain. The name Great Britain originates with the Picts, a people present in Britain before the Celts. The Britons and early Welsh of the south knew them, in the P-Celtic form of "Cruithne", as Prydyn; the terms "Britain" and "Briton" come from the same root. "It was itself named Albion, while all the islands about which we shall soon briefly speak were called the Britanniae." The name Albion was taken by medieval writers from Pliny and Ptolemy.

The name is perhaps of Celtic origin or older, from the Proto-Indo-European root that denotes both "white" and "mountain", but the Romans took it as connected with albus (white), in reference to the chalk "White Cliffs of Dover", and Alfred Holder's Alt-Keltischer Sprachschatz (1896) unhesitatingly translates it Weissland ("whiteland"). The early writer (6th century BC) whose periplus was translated by Avienus at the end of the 4th century AD (see Massaliote Periplus) does not use the name Britannia; he speaks of nesos 'Iernon kai 'Albionon (island of the Ierni and the Albiones). So Pytheas of Massilia (4th century BC) speaks of Albion and 'Ierne. From the fact that there was a tribe called the Albiones on the north coast of Spain in Asturias, some scholars have placed Albion in that neighbourhood (see G. F. Unger, Rhein. Mus. xxxviii., 1883, pp. 156-196).