- from Anglo-French Bretun,
- from Latin Brittonem (nominative Britto, misspelled Brito in MSS) - "a member of the tribe of the Britons",
- from the Celtic *Britt-os - name of the Celtic inhabitants of Britain and southern Scotland before the 5c. AD Anglo-Saxon invasion drove them into Wales, Cornwall, and a few other corners.
- In 4c. BC Greek they are recorded as Prittanoi, which is said to mean "tattooed people".
Exclusively in historical use after Old English period;
revived when James I was proclaimed King of Great Britain in 1604, and made official at the union of England and Scotland in 1707.