ドクッ

ドクッ, どくっ, ドクっdoku

adverb

  1. with a heavy thump
  2. with a thud
  3. with a palpitation

Study it in Yanamino

Data from JMdict, KANJIDIC2 (EDRDG), KanjiVG, CC-CEDICT and Make Me a Hanzi. Sources and licences