curvilinear vs spheroidal

curvilinear

adj

  • Having bends; curved; curvilineal. 

  • Formed by curved lines. 

spheroidal

adj

  • Like a spheroid; roughly spherical. 

noun

  • A spheroid 

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