axial vs essential

axial

adj
  • Relating to, resembling, or situated on an axis 

  • Belonging to the axis of the body, or to the axis of any appendage or organ 

  • In the same direction as the axis, parallel to the axis. 

  • oriented close to the axis running through the centre of a cyclohexane ring, as opposed to equatorial. See w:Axial bond. 

noun
  • A plane parallel to the surface of a tooth. 

  • A flight feather that appears between the primaries and secondaries on some birds. 

essential

adj
  • 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. 

  • 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. 

  • Idiopathic. 

noun
  • A necessary ingredient. 

  • A fundamental ingredient. 

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