TNabbr. TennesseeAmerican 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.tn abbreviation for trillion tn the internet domain name for (Computer Science) Tunisia TN abbreviation for 1. Tennessee 2. (Government, Politics & Diplomacy) Tunisia (international car registration) Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014TN Tennessee. tn. 1. ton. 2. town. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.