doka-tto
Dropping one's body weight heavily into a seat. Also describes placing something down with a thud.
💡Coming home exhausted — 'He sat doka-tto on the sofa and didn't move.'
疲れてソファにどかっと座った。
Exhausted, I sat doka-tto heavily on the sofa.
He ___ dropped into the chair after the long meeting.
長い会議の後、椅子に○○と座り込んだ。