holt vs monadnock

holt

noun
  • A small piece of woodland or a woody hill; a copse. 

  • The lair of an animal, especially of an otter. 

monadnock

noun
  • A hill or mountain standing isolated above a predominantly flat plain. 

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