taboo vs unlawful

taboo

adj
  • Culturally forbidden. 

  • Excluded or forbidden from use, approach or mention. 

verb
  • To ban. 

  • To avoid. 

  • To mark as taboo. 

noun
  • An inhibition or ban that results from social custom or emotional aversion. 

  • Something which may not be used, approached or mentioned because it is sacred. 

unlawful

adj
  • Prohibited; not permitted by law (either civil or criminal law; see illegal). 

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