coercive vs optional

coercive

adj
  • Such that the ratio of |F(x)| to x approaches infinity as x approaches infinity. 

  • Displaying a tendency or intent to coerce. 

optional

noun
  • In various programming languages, a kind of variable that is assigned a specific data type but may or may not hold an actual value. 

  • Something that is not compulsory, especially part of an academic course. 

adj
  • Not compulsory; left to personal choice; elective. 

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