I·da·ho 1 (??d?-h??) Abbr. ID or Id. A state of the northwest United States. It was admitted as the 43rd state in 1890. Explored by the Lewis and Clark expedition in 1805, the region was held jointly by Great Britain and the United States from 1818 to 1846. Idaho became a separate territory in 1863. Boise is the capital and the largest city.I?da·ho?an adj. & n.I·da·ho 2 (??d?-h??)n. See russet Burbank.[After Idaho, where it is chiefly grown.]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.Idaho (?a?d??h??) n (Placename) a state of the northwestern US: consists chiefly of ranges of the Rocky Mountains, with the Snake River basin in the south; important for agriculture (Idaho potatoes), livestock, and silver-mining. Capital: Boise. Pop: 1 366 332 (2003 est). Area: 216 413 sq km (83 557 sq miles). Abbreviation: Id., Ida. or ID (with zip code)Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014I?da?ho (?a? d??ho?) n. a state in the NW United States. 1,293,953; 83,557 sq. mi. (216,415 sq. km). Cap.: Boise. Abbr.: ID, Ida. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.Idaho – Shoshone for “light on mountains.”See also related terms for mountains.Farlex Trivia Dictionary. © 2012 Farlex, Inc. All rights reserved.