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.
In anime production, inbetweening determines the smoothness of movement.
He is in charge of the inbetweening work.
quiet move
In Othello/Reversi, a move that flips few discs, often played in the middle of the board to maintain a stable position.
By playing a quiet move, I avoided giving my opponent a good move.
Standard spelling with full okurigana.
Irregular okurigana variant; seen in some contexts but less standard.
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.