An onomatopoeic adverb for a heavy thud or the action of plopping down forcefully; expresses a sudden, heavy impact or movement.
彼は疲れて椅子にどかっと座った。
He plopped down into the chair, tired.
箱が床にどかっと落ちた音でびっくりした。
I was startled by the thud when the box fell onto the floor.
荷物がどかっと積まれて通路がふさがれた。
The luggage was dumped in a heap and blocked the aisle.