buckram vs hardened

buckram

verb
  • To stiffen with or as if with buckram. 

noun
  • A coarse cloth of cotton, linen or hemp, stiffened with size or glue, used in bookbinding to cover and protect the books, in garments to keep them in the form intended, and for wrappers to cover merchandise. 

  • A plant, Allium ursinum, also called ramson, wild garlic, or bear garlic. 

hardened

adj
  • Inured; toughened. 

  • Firmly established or unlikely to change; inveterate. 

  • Having extra defences against attack; highly fortified. 

  • Unfeeling; pitiless; callous. 

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