An onomatopoeic word expressing the sound or impact of something heavy falling with a thud; can also figuratively describe a heavy emotional blow.
箱が床に落ちてズシンと音がした。
A box fell to the floor with a heavy thud.
彼の一言で胸にズシンと来た。
His remark hit me hard in the chest (I felt a heavy emotional impact).
荷物を置いたら、テーブルがズシンと揺れた。
When I put down the luggage, the table shook with a thud.