medial vs vertex

medial

noun
  • One or more letters that occur in the middle of a word. 

  • Any of various things that occur in the middle. 

adj
  • Of or pertaining to the media and/or the areas of the wing next to it. 

  • Pertaining to the inside; closer to the median plane of the body or the midline of an organ. 

  • (of a speech sound) In the middle of a word. 

  • Closer to the addressee. 

  • Of or pertaining to a mean or average. 

  • Pertaining to the middle layer of a blood vessel, to its tunica media. 

  • (of a consonant) Central: produced when air flows across the center of the mouth over the tongue. 

vertex

noun
  • A sharp downward point opposite a crotch, as in the letters "V" and "W" but not "Y". 

  • One of the elements of a graph joined or not by edges to other vertices. 

  • A point in 3D space, usually given in terms of its Cartesian coordinates. 

  • The point where the surface of a lens crosses the optical axis. 

  • An interaction point. 

  • The point at which an axis meets a curve or surface. 

  • The common point of the two rays that form an angle. 

  • The point where the prime vertical meets the ecliptic in the western hemisphere of a natal chart. 

  • A point on the curve with a local minimum or maximum of curvature. 

  • The highest surface on the skull; the crown of the head. 

  • The highest point, top or apex of something. 

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