axial vs middle

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. 

middle

adj
  • Located in the middle; in between. 

  • Pertaining to the middle voice. 

  • Central. 

noun
  • A centre, midpoint. 

  • The part between the beginning and the end. 

  • The middle stump. 

  • The central part of a human body; the waist. 

  • The middle voice. 

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