noun
professional shogi player; professional go player
Refers to a person who makes a living playing shogi or go at a professional level. The context usually makes it clear which game is meant.
彼は若くして棋士になった。
He became a professional shogi/go player at a young age.
棋士の対局は長時間に及ぶことが多い。
Matches between professional shogi/go players often last for many hours.