adverb
with a clatter; with a clunk
Onomatopoeic adverb describing a single, sharp, hard sound of something hitting or falling, often a small object. Related to かたり, which can describe a lighter or more continuous clattering.
See also: かたり
机の上にペンがかたっと落ちた。
The pen fell onto the desk with a clatter.
ドアの向こうでかたっと物音がした。
There was a clunking sound from behind the door.