addition vs essential

addition

noun
  • The act of adding anything. 

  • The arithmetic operation of adding. 

  • A dot at the right side of a note as an indication that its sound is to be lengthened one half. 

  • Anything that is added. 

  • A title annexed to a person's name to identify him or her more precisely. 

  • Something added to a coat of arms, as a mark of honour. 

essential

adj
  • Necessary. 

  • Necessary for survival but not synthesized by the organism, thus needing to be ingested. 

  • Being in the basic form; showing its essence. 

  • Really existing; existent. 

  • Very important; of high importance. 

  • Having the nature of essence; not physical. 

  • Such that each complementary region is irreducible, the boundary of each complementary region is incompressible by disks and monogons in the complementary region, and no leaf is a sphere or a torus bounding a solid torus in the manifold. 

  • Idiopathic. 

noun
  • A necessary ingredient. 

  • A fundamental ingredient. 

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