Dictionary.com
definitions

International Master

noun
  1. a chess player of high ability but below the level of International Grand Master, as determined through specified types of international competitions.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for international master

International Master

noun
  1. chess the second highest title awarded by the FIDE to a player: won by obtaining a certain number of points during specific international chess tournamentsOften shortened to: master Compare grandmaster (def. 2)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012