echoic vs plangent

echoic

adj
  • Imitative of a sound; onomatopoeic. 

  • Of or pertaining to an echo 

plangent

adj
  • Having a loud, mournful sound. 

  • Beating, dashing, as waves. 

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