an onomatopoeia indicating a sudden clunk or clank; the sound/feel of something dropping or hitting with a thud.
古い棚ががたっと倒れた。
The old shelf toppled over with a clunk.
彼は疲れて椅子にがたっと座り込んだ。
He flopped down into the chair in exhaustion.
強い風で窓ががたっと閉まった。
The window slammed shut with a clatter from the strong wind.
used mimetically to describe a sudden drop (e.g., in sales, energy, or performance).
新製品発売後、先月の売上ががたっと落ちた。
After the new product launch, last month's sales fell off sharply.
疲れで集中力ががたっと低下した。
My concentration suddenly dropped due to fatigue.