agendum vs operation

agendum

noun
  • Something to be done; a practical duty, rather than an article of faith. 

operation

noun
  • A planned undertaking. 

  • The method or practice by which actions are done. 

  • The act or process of operating; agency; the exertion of power, physical, mechanical, or moral. 

  • A procedure for generating a value from one or more other values (the operands); 

  • A military campaign (e.g. Operation Desert Storm) 

  • A business or organization. 

  • a function which maps zero or more (but typically two) operands to a single output value. 

  • The method by which a device performs its function. 

  • A surgical procedure. 

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