complete victory; clean sweep; perfect record
Used when someone wins every single match or contest, or achieves a flawless record without any losses. Often used in sports, games, or competitions.
He won the championship with a perfect record this season.
It's hard to achieve a clean sweep in this game.
Compound of 丸 (まる, 'circle', here meaning 'complete' or 'perfect') and 勝ち (かち, 'winning'). The exact historical derivation is uncertain, but the word is used to describe a perfect winning record.