Great Britain

noun
1.
an island of NW Europe, separated from the mainland by the English Channel and the North Sea: since 1707 the name has applied politically to England, Scotland, and Wales. 88,139 sq. mi. (228,280 sq. km).
Compare United Kingdom.
British Dictionary definitions for Great Britain

Great Britain

noun
1.
England, Wales, and Scotland including those adjacent islands governed from the mainland (i.e. excluding the Isle of Man and the Channel Islands). The United Kingdom of Great Britain was formed by the Act of Union (1707), although the term Great Britain had been in use since 1603, when James VI of Scotland became James I of England (including Wales). Later unions created the United Kingdom of Great Britain and Ireland (1801) and the United Kingdom of Great Britain and Northern Ireland (1922). Pop: 57 851 100 (2003 est). Area: 229 523 sq km (88 619 sq miles) See also United Kingdom
Word Origin and History for Great Britain

c.1400, Grete Britaigne. As opposed to Brittany.