-teen n combining form (Mathematics) ten: added to modified forms of the numbers 3 to 9 to form the numbers 13 to 19 [Old English -t?ne, -t?ne] -teenth adj combining formCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014teen2 (tin) adj. 1. teenage. n. 2. a teenager. [1940?45] teen1 (tin) n. Archaic. grief. [before 1000; Middle English tene, Old English t?ona] -teen a suffix used to form cardinal numerals from 13 to 19. [Middle English, Old English -t?ne, comb. form of ten] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.