From Middle Welsh Prydein, from early Britannic *Pritanī, a variant of *Pritenī, which survives in Prydyn (“Picts”) and as an early borrowing in Old Irish Cruthin, Irish Cruithne (“Picts”). The Modern Welsh continuation of Latin Brittānia, in contrast, is Brython.
In medieval texts, the term often refers to the northernmost part of the island, beyond the Forth and Clyde. Where the island as a whole is meant, the phrase Ynys Prydain (Latin insula Britanniae, "Isle of Britain") is commonly used.
- Prydain Fawr (“Great Britain”)