A-game (??g?m?)n. The best performance a competitor is capable of in a sports contest: We’ll have to bring our A-game to defeat the league champions.[From the use of the letter A to indicate the best.]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.