annular vs curvilinear

annular

adj
  • Banded or marked with circles. 

  • Pertaining to, or having the form of, a ring; ring-shaped; in the shape of an annulus. 

curvilinear

adj
  • Formed by curved lines. 

  • Having bends; curved; curvilineal. 

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