echoic vs imitative

echoic

adj
  • Imitative of a sound; onomatopoeic. 

  • Of or pertaining to an echo 

imitative

adj
  • Imitating; copying; not original. 

  • Modelled after another thing. 

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