doctrine vs fundamental

doctrine

noun
  • The body of teachings of an ideology, most often a religion, or of an ideological or religious leader, organization, group, or text. 

  • A self-imposed policy governing some aspect of a country's foreign relations, especially regarding what sort of behavior it will or will not tolerate from other countries. 

  • A belief or tenet, especially about philosophical or theological matters. 

fundamental

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

  • The lowest frequency of a periodic waveform. 

  • The lowest partial of a complex tone. 

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

  • essential; extremely important 

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