kerplunk UK /kəˈplʌŋk/US /kə(ɹ)ˈplʌŋk/noun 2exclamation 1verb 1forms 3 noun2 •(informal) A sound of someone or something falling and landing heavily.If my life were a Saturday-morning cartoon, you would have heard a loud kerplunk as my stomach dropped. My poor starving stomach. It was under such stress already, and now this. — 2005 •(slang, figurative) A disappointment which comes as a surprise. exclamation1 •Used to indicate a thudding sound. verb1 •(informal) To make the sound of falling and landing heavily; to thud. formskerplunked · kerplunking · kerplunks