copycat vs echoic

copycat

adj
  • Imitative; unoriginal. 

verb
  • To act as a copycat; to copy in a shameless or derivative way 

noun
  • One who imitates or plagiarizes others' work. 

  • A criminal who imitates the crimes of another; specifically, a criminal who commits the same crime, especially a highly-publicized one, that has just been or recently committed by someone else. 

echoic

adj
  • Imitative of a sound; onomatopoeic. 

  • Of or pertaining to an echo 

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