grand master or grand·mas·ter (gr?nd?m?s?t?r)n.1. A chess player regarded as having the highest level of ability.2. A person of the highest competence or achievement in a field.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.grandmaster (??rænd?m??st?) n1. (Chess & Draughts) chess a. one of the top chess players of a particular countryb. (capital as part of title): Grandmaster of Russia. 2. (Chess & Draughts) chess Also called: International Grandmaster a player who has been awarded the highest title by the Fédération Internationale des Échecs3. a leading exponent of any of various artsCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014