plip vs thump

plip

noun
  • A light sound or action like liquid hitting a surface. 

verb
  • To make the sound of liquid hitting a hard surface. 

  • To lock or unlock using a remote control locking device. 

thump

noun
  • A blow that produces a muffled sound. 

  • The sound of such a blow; a thud. 

verb
  • To throb with a muffled rhythmic sound. 

  • To hit (someone or something) as if to make a thump. 

  • To cause to make a thumping sound. 

  • To thud or pound. 

How often have the words plip and thump occurred in a corpus of books? (source: Google Ngram Viewer )