annular vs circular

annular

adj
  • Banded or marked with circles. 

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

circular

adj
  • In the shape of, or moving in a circle. 

  • Referring back to itself, so as to prevent computation or comprehension; infinitely recursive. 

  • Circuitous or roundabout. 

  • Of or relating to a circle. 

  • Distributed to a large number of persons. 

verb
  • To extend in a circular direction. 

  • To distribute circulars to or at. 

noun
  • Synonym of flyer: a printed advertisement, directive, or notice intended for mass circulation. 

  • A shuttle bus with a circular route. 

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