downtone vs relax

downtone

verb
  • To tone down; to make less emphatic or significant; to downplay. 

relax

verb
  • To make something less severe or tense. 

  • To become loose. 

  • To become less severe or tense. 

  • To make something (such as codes and regulations) more lenient. 

  • To calm down. 

  • To relieve (something) from stress. 

  • To make something loose. 

  • To become more lenient. 

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