mountainous vs pyramidal

mountainous

adj
  • Resembling a mountain, especially in size; huge; towering. 

  • Very difficult. 

  • Having many mountains; characterized by mountains; of the nature of a mountain; rough (terrain); rocky. 

pyramidal

adj
  • Pyramid-shaped. 

  • Tetragonal. 

noun
  • One of the carpal bones. 

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