fundamental vs substantial

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. 

substantial

adj
  • Most important; essential. 

  • Not imaginary; real; actual; true; veritable. 

  • Having a substance; actually existing. 

  • Corporeal; material; firm. 

  • Possessed of goods or an estate; moderately wealthy. 

  • Satisfying; having sufficient substance to be nourishing or filling. 

  • Large in size, quantity, or value; ample; significant. 

  • Having good substance; strong; stout; solid; firm. 

noun
  • Anything having substance; an essential part. 

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