adv. 1.with a short hollow thud plunk n. 1.a hollow twanging sound 2.(baseball) hitting a baseball so that it drops suddenly plunk v. 1.make or move along with a sound as of a horse's hooves striking the ground 2.set (something or oneself) down with or as if with a noise 3.drop steeply 4.pull lightly but sharply with a plucking motion