draughtproof vs lock down

draughtproof

verb
  • To seal an opening, so as to prevent the entry of draughts. 

adj
  • That prevents the entry of draughts. 

lock down

verb
  • To secure; to make people stay locked indoors for their safety. 

  • To make an arrangement secure, definite, or permanent; to fix. 

  • To cause another to enter into an exclusive romantic relationship. 

  • To travel through a flight of locks on a waterway in a downhill direction. 

  • To limit the use of a computer network to only users with permission. 

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