hoar vs hoarfrost

hoar

adj

  • Hoarily bearded. 

  • Of a white or greyish-white colour. 

noun

  • A white or greyish-white colour. 

  • Hoariness; antiquity. 

hoarfrost

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