covenant vs undertaking

covenant

noun
  • A promise, incidental to a deed or contract, either express or implied. 

  • An incidental clause in an agreement. 

  • An agreement to do or not do a particular thing. 

  • A pact or binding agreement between two or more parties. 

verb
  • To enter into, or promise something by, a covenant. 

  • To enter a formal agreement. 

  • To make a stipulation. 

  • To bind oneself in contract. 

undertaking

noun
  • A promise or pledge; a guarantee. 

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

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

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

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