relax vs stand down

relax

verb
  • To become less severe or tense. 

  • To become loose. 

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

  • To calm down. 

  • To relieve (something) from stress. 

  • To make something less severe or tense. 

  • To make something loose. 

  • To become more lenient. 

stand down

verb
  • To wait; to stop pursuing, stop fighting, or relax from a heightened readiness posture. 

  • To withdraw or retire from a position or from a team. 

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