helical vs radial

helical

adj
  • In the shape of a helix. 

radial

adj
  • Of, or relating to the radius (vein), and/or the wing areas next to it. 

  • Developing uniformly on all sides. 

  • Moving along a radius. 

  • Of, or relating to the radius bone. 

  • Arranged like rays that radiate from, or converge to a common centre. 

noun
  • A radial tire / radial tyre. 

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