concordat vs engagement

concordat

noun
  • A formal agreement between two parties, especially between a church and a state; specifically, an agreement between the Pope and a government. 

engagement

noun
  • The period of time when marriage is planned or promised. 

  • The point at which the fencers are close enough to join blades, or to make an effective attack during an encounter. 

  • Connection or attachment. 

  • The feeling of being compelled, drawn in, connected to what is happening, interested in what will happen next. 

  • An appointment, especially to speak or perform. 

  • In any situation of conflict, an actual instance of active hostilities. 

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