Mon-Khmer (m?n?km?r?) n. A subfamily of the Austroasiatic language family that includes Mon, Khmer, and other languages of Southeast Asia. Mon?-Khmer? adj. 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.Mon-Khmer n (Languages) a family of languages spoken chiefly in Cambodia, Myanmar, and Assam; probably a member of the Austro-Asiatic phylum adj (Languages) of or belonging to this family of languages Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Mon-Khmer (?mo?n?km??r, -k??m??r) n. a language family of Southeast Asia, a branch of the Austroasiatic family, that includes Mon, Khmer, and many other languages of southeast Asia. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.