grandmaster

Short definition from Wiktionary

Noun

1. 1
   Alternative spelling of Grandmaster.
2. 2
   A master in a field, whose skills or accomplishments exceed those of other masters.
3. 3
   A player of the highest rank, as determined by FIDE, with an Elo rating of at least 2500.
4. 4
   Ellipsis of Grandmaster of the Soviet Union; USSR champion.