plapper,v.|ˈplæpə(r)| [imit.: see S.N.D.] intr. To make sounds with the lips. 1866W. Gregor in Trans.Philol.Soc. 127 Plapper,..to make a noise with the lips.1922Joyce Ulysses 258 She took no notice while he read by rote a solfa fable for her, plappering flatly.