fundamental vs imperative

fundamental

adj
  • essential; extremely important 

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

noun
  • 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 

  • The lowest partial of a complex tone. 

imperative

adj
  • Essential; crucial; extremely important. 

  • Having semantics that incorporates mutable variables. 

  • Expressing a command; authoritatively or absolutely directive. 

  • Of, or relating to the imperative mood. 

noun
  • A verb in imperative mood. 

  • The grammatical mood expressing an order (see jussive). In English, the imperative form of a verb is the same as that of the bare infinitive. 

  • An essential action, a must: something which is imperative. 

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