also: どっくん
adverb, adverb taking the 'to' particle, noun
heavy heartbeat; thumping; pounding
Mimetic word describing a strong, sudden heartbeat, often from surprise, fear, or excitement. Can be used adverbially with と or as a noun.
My heart went thump.
My chest pounds with a heavy thump-thump.
Katakana variant of どっくん, used for emphasis.
Mimetic word derived from the sound of a heavy heartbeat. The exact origin is uncertain, but it is a conventionalized onomatopoeia in Japanese.