adverb taking the 'to' particle
with a plop; with a plonk; with a flop
Mimetic adverb describing a small, soft object falling or dropping lightly, often with a gentle sound.
熟した柿がポトリと地面に落ちた。
A ripe persimmon fell to the ground with a plop.
彼女はポトリと涙をこぼした。
She shed a tear with a plop.
Onomatopoeic formation from the sound of a light object dropping.