mandatory vs servile

mandatory

adj
  • Of, being or relating to a mandate. 

  • Obligatory; required or commanded by authority. 

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

servile

noun
  • A slave; a menial. 

  • An element which forms no part of the original root. 

adj
  • Of or pertaining to a slave. 

  • Not belonging to the original root. 

  • Slavish or submissive. 

  • Not sounded, but serving to lengthen the preceding vowel, like the e in tune. 

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