lighten vs obfuscate

lighten

verb
  • To make brighter or clearer; to illuminate. 

  • 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 become less serious or more cheerful. 

  • To make light or lighter in weight. 

obfuscate

verb
  • To make dark; to overshadow. 

  • To deliberately make more confusing in order to conceal the truth. 

  • To alter code while preserving its behavior but concealing its structure and intent. 

  • Before leaving the scene, the murderer set a fire in order to obfuscate any evidence of their identity. 

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