drawing board vs impediment

drawing board

noun
  • The planning stage of a project. 

  • A plane surface or table to which paper can be fastened for drawing purposes. 

impediment

noun
  • A hindrance; that which impedes or obstructs progress. 

  • Baggage, especially that of an army; impedimenta. 

  • A disability, especially one affecting the hearing or speech. 

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