plunk / pləngk/ inf. • v. 1. [intr.] play a keyboard or plucked stringed instrument, esp. in an unexpressive or unskilled way.2. [tr.] hit (someone) abruptly.3. (also plank) [tr.] put or set (something) down heavily or abruptly: she plunked her purse on top of the bar. ∎ pay (money) on the spot or abruptly: I gladly plunked down my ten dollars. ∎ (plunk oneself down) sit down in a hurried or undignified way: she plunks herself down on the stool.• n. 1. the sound made by abruptly plucking a string of a stringed instrument.2. a heavy blow.3. an act of setting something down heavily.DERIVATIVES: plunk·er n.