adverb taking the 'to' particle, adverb
Mimetic word for a heavy, dull impact sound, like something solid dropping or hitting a surface. Often used with と.
本が床にごとんと落ちた。
The book fell to the floor with a thump.
大きな石がごとんと音を立てて転がった。
A large rock rolled with a clunk.
Onomatopoeic formation; the exact origin is uncertain.