a district of E Northern Ireland, in Co Down. Pop: 66 076 (2003 est). Area: 85 sq km (33 sq miles)
Castlereagh in British English2
(ˈkɑːsəlˌreɪ)
noun
Viscount. title of Robert Stewart, Marquis of Londonderry. 1769–1822, British statesman: as foreign secretary (1812–22) led the Grand Alliance against Napoleon and attended the Congress of Vienna (1815)
Castlereagh in American English
(ˈkæsəlˌreɪ; ˈkɑsəlˌreɪ)
Viscount(Robert Stewart) 2d Marquis of Londonderry 1769-1822; Brit. statesman, born in Ireland