noun
break and run out (in billiards)
A billiards term for when a player breaks and then pockets all required balls without giving the opponent a turn. Used in games like 9-ball and 8-ball.
彼はマスワリで試合を決めた。
He won the match with a break and run out.
マスワリを達成するには正確なショットが必要だ。
You need accurate shots to achieve a break and run out.
From マス (masu, 'break' in billiards) + 割り (wari, 'splitting' or 'completing'), referring to clearing the table after the break. The exact derivation is uncertain, but it is a specialized billiards term.