autonomous vs obligatory

autonomous

adj
  • Self-governing. Intelligent, sentient, self-aware, thinking, feeling, governing independently. 

  • Acting on one's own or independently; of a child, acting without being governed by parental or guardian rules. 

  • Used with no subject, indicating an unknown or unspecified agent; used in similar situations as the passive in English (the difference being that the theme in the English passive construction is the subject, while in the Celtic autonomous construction the theme is the object and there is no subject). 

obligatory

adj
  • Requiring a matter or obligation. 

  • Imposing obligation, legally, morally, or otherwise; binding; mandatory. 

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