Tex·ar·kan·a (t?k?sär-k?n??) A city of extreme northeast Texas adjacent to Texarkana, Arkansas. It grew after the coming of the railroad in the 1870s.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.