vocation vs vocative

vocation

noun
  • An occupation for which a person is suited, trained or qualified. 

  • An inclination to undertake a certain kind of work, especially a religious career; often in response to a perceived summons; a calling. 

vocative

noun
  • The vocative case 

  • A word in the vocative case 

  • Something said to (or as though to) a particular person or thing; an entreaty, an invocation. 

adj
  • Of or pertaining to calling; used in calling or vocation. 

  • Used in address; appellative (said of that case or form of the noun, pronoun, or adjective, in which a person or thing is addressed). For example "Domine, O Lord" 

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