i.e.abbr. Latin id est (that is)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.i.e. abbreviation for (Literary & Literary Critical Terms) id est [Latin: that is (to say); in other words]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014namely – i.e.Namely and i.e. are both used to give more information about something that you have just mentioned.You use namely to say exactly what you mean when you have just referred to something in a general or indirect way.You use i.e. when you are giving an explanation of a word or expression that you have just used.