Northern Ireland A division of the United Kingdom in the northeast section of the island of Ireland. It was colonized by the British in the 1600s and remained in the United Kingdom after the establishment of the independent Republic of Ireland. Civil strife between the Protestant majority and Catholic minority of Northern Ireland erupted frequently from the late 1960s until the signing of a power-sharing agreement (1998). Belfast is the capital and the largest city.Northern Ire?land·er n.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.Northern Ireland n (Placename) that part of the United Kingdom occupying the NE part of Ireland: separated from the rest of Ireland, which became independent in law in 1920; remained part of the United Kingdom, with a separate Parliament (Stormont), inaugurated in 1921, and limited self-government; scene of severe conflict between Catholics and Protestants, including terrorist bombing from 1969; direct administration from Westminster from 1972; assembly and powersharing executive established in 1998?99 following the Good Friday Agreement of 1998, suspended in 2002, and reinstated 2007. Capital: Belfast. Pop: 1 810 863 (2011 est). Area: 14 121 sq km (5452 sq miles) Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014North?ern Ire?land n. a political division of the United Kingdom, in the NE part of Ireland. 1,594,400; 5452 sq. mi. (14,121 sq. km). Cap.: Belfast. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.