glacial vs hibernal

glacial

adj
  • Of, or relating to glaciers. 

  • Very slow. 

  • Having the appearance of ice. 

  • Cool and unfriendly. 

  • Cold and icy. 

noun
  • A glacial period (colloquially known as an ice age). 

hibernal

adj
  • Of or pertaining to winter; brumal or hiemal 

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