calm vs lighten

calm

verb
  • To become calm. 

  • To make calm. 

noun
  • The state of being calm; peacefulness; absence of worry, anger, fear or other strong negative emotion. 

  • A period of time without wind. 

  • The state of being calm; absence of noise and disturbance. 

adj
  • with few or no waves on the surface; not rippled. 

  • Peaceful, quiet, especially free from anger and anxiety. 

  • Free of noise and disturbance. 

  • Without wind or storm. 

lighten

verb
  • To become less serious or more cheerful. 

  • To become light or lighter in weight. 

  • To become brighter or clearer; to brighten. 

  • To make less serious or more cheerful. 

  • To illuminate with knowledge; to enlighten. 

  • To descend; to light. 

  • To emit or disclose in, or as if in, lightning; to flash out, like lightning. 

  • To alleviate; to reduce the burden of. 

  • To make brighter or clearer; to illuminate. 

  • To make light or lighter in weight. 

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