hoar vs verglas

hoar

noun

  • A white or greyish-white colour. 

  • Hoariness; antiquity. 

adj

  • Hoarily bearded. 

  • Of a white or greyish-white colour. 

verglas

noun

  • silver frost 

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