noun
inbetween; tweening
Animation term for the frames drawn between keyframes to create smooth motion. Also used as a noun for the process or the resulting frames.
アニメの制作では、中割りが動きの滑らかさを決める。
In anime production, inbetweening determines the smoothness of movement.
彼は中割りの作業を担当している。
He is in charge of the inbetweening work.
noun
quiet move
In Othello/Reversi, a move that flips few discs, often played in the middle of the board to maintain a stable position.
中割りを打つことで、相手に手を渡さずに済んだ。
By playing a quiet move, I avoided giving my opponent a good move.
Compound of 中 (naka, 'middle') and 割り (wari, 'splitting' or 'dividing'), referring to inserting something in between. The animation sense comes from inserting frames between keyframes; the Othello sense comes from playing a move in the middle that splits the board quietly.