fundamental vs keynote

fundamental

noun
  • The lowest partial of a complex tone. 

  • The lowest frequency of a periodic waveform. 

  • A main or major principle, rule, law, etc. which serves as the foundation or basis of a system; an essential part 

adj
  • Related to a foundation. base, or basis; serving as a foundation. 

  • essential; extremely important 

keynote

noun
  • The note on which a musical key is based; the tonic. 

  • The main theme of a speech, a written work, or a conference. 

  • A speech that sets the main theme of a conference or other gathering; a keynote speech or keynote address. 

verb
  • To deliver a speech that sets the main theme of a conference or other gathering. 

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