chatelaine vs keychain

chatelaine

noun
  • A chain or clasp worn at the waist by women with handkerchief, keys, etc., attached, supposed to resemble the chain of keys once worn by medieval chatelaines. 

  • A similar thing in miniature attached to a watchchain. 

keychain

noun
  • An ornamental piece holding such a chain or ring. 

  • A chain or ring to which a key may be attached. 

  • A digital repository for the storage of cryptographic keys. 

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