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.
心臓がどくんと鳴った。
My heart went thump.
どくん、どくんと胸が高鳴る。
My chest pounds with a heavy thump-thump.
どきどき describes a rapid, light, excited heartbeat, while どくん emphasizes a single heavy thump or slower, stronger beats.
ばくばく suggests a very fast, pounding heartbeat often from extreme fear or physical exertion, more intense and rapid than どくん.
Mimetic word derived from the sound of a heavy heartbeat. The exact origin is uncertain, but it is a conventionalized onomatopoeia in Japanese.