Fusen (不戦) is called when the opponent is absent for the scheduled bout (by default). There are also corresponding terms for winning by default (不戦勝, fusenshō) and losing by default (不戦敗, fusenpai). Wins and losses by fusen are also visually recorded as black and white squares rather than the normal black and white circles.

From English Wikipedia (article), CC BY-SA 4.0.