groan vs waul

groan

verb
  • To make a groan. 

  • To seemingly creak under the strain of being heavily laden. 

noun
  • A low, mournful sound uttered in pain or grief. 

  • A low, guttural sound uttered in frustration, disapproval, or ecstasy. 

  • A low creaking sound from applied pressure or weight. 

waul

verb
  • To wail, to cry plaintively. 

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