United KingdomUnited Kingdom
- country in W Europe, consisting of Great Britain & Northern Ireland: 94,526 sq mi (244,820 sq km); cap. Londonin full United Kingdom of Great Britain and Northern Ireland
- country (1801-1921) consisting of Great Britain & Irelandin full United Kingdom of Great Britain and Ireland
or United Kingdom of Great Britain and Northern Ireland
Abbr. UK A country of western Europe comprising England, Scotland, Wales, and Northern Ireland. Beginning with the kingdom of England, it was created by three acts of union: with Wales (1536), Scotland (1707), and Ireland (1801). At the height of its power in the 1800s, it ruled an empire that spanned the globe. London is the capital and the largest city.