buckram vs unflexible

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. 

verb
  • To stiffen with or as if with buckram. 

unflexible

adj
  • Not flexible. 

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