mandatory vs obedient

mandatory

noun
  • A sign or line that require the path of the disc to be above, below or to one side of it. 

adj
  • Of, being or relating to a mandate. 

  • Obligatory; required or commanded by authority. 

obedient

adj
  • Willing to comply with the commands, orders, or instructions of those in authority. 

noun
  • One who obeys. 

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