mission vs undertaking

mission

noun
  • A set of tasks that fulfills a purpose or duty; an assignment set by an employer, or by oneself. 

  • Religious evangelism. 

  • An infrequent gathering of religious believers in a parish, usually part of a larger regional event with a central theme. 

  • A number of people appointed to perform any service; a delegation; an embassy. 

  • A settlement or building serving as a base for missionary work. 

  • Third World charities, particularly those which preach as well as provide aid. 

verb
  • To do missionary work, proselytize. 

  • To send on a mission. 

undertaking

noun
  • That which is undertaken; any business, work, or project which a person engages in, or attempts to perform; an enterprise. 

  • A promise or pledge; a guarantee. 

  • The business of an undertaker, or the management of funerals. 

  • The act of one who undertakes (in either sense). 

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