Tai (t?)n. pl. Tai or Tais 1. A subfamily of Tai-Kadai languages spoken in southeast Asia and southern China that includes Thai, Lao, and Shan.2. A member of any of the Tai-speaking peoples of Thailand, Myanmar (Burma), Laos, China, and Vietnam.adj. Of or relating to Tai, its speakers, or their culture.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.Tai (ta?) adj, n (Languages) a variant spelling of ThaiTAI abbreviation for (General Physics) International Atomic Time Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Tai (ta?, ?t? i) n., pl. Tais. 1. a language family of mainland Southeast Asia and S China, including Thai, Lao, and Shan. 2. Thai (defs. 1, 2). Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.