toroid vs torus

toroid

noun
  • A ring-shaped object whose surface is a torus. 

  • A surface generated by a closed curve (especially a circle) rotating about, but not intersecting or containing, an axis in its own plane. 

torus

noun
  • A ring-shaped object, especially a large ring-shaped chamber used in physical research. 

  • The thickening of a membrane closing a wood-cell pit (as of gymnosperm tracheids) having the secondary cell wall arched over the pit cavity. 

  • A rounded ridge of bone or muscle, especially one on the occipital bone. 

  • {{lb|en|topology|in combination|n-torus|4-torus|etc.}} The product of the specified number of circles. 

  • A topological space which is a product of two circles. 

  • A large convex molding, typically semicircular in cross section, which commonly projects at the base of a column and above the plinth. 

  • The end of the peduncle or flower stalk to which the floral parts (or in the Asteraceae, the florets of a flower head) are attached. 

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