annular vs spheroidal

annular

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

  • Banded or marked with circles. 

spheroidal

adj
  • Like a spheroid; roughly spherical. 

noun
  • A spheroid 

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