brick wall vs flagpole

brick wall

noun
  • An obstacle. 

  • Used other than figuratively or idiomatically: see brick, wall. A wall made of bricks. 

  • Someone who is silent or unresponsive. 

  • A type of anti-aliasing filter with a steep cutoff. 

verb
  • To halt or limit abruptly. 

  • To build a brick wall around. 

  • To be uncooperative and unresponsive. 

  • To filter using a brick wall filter. 

flagpole

noun
  • A tall pole up which one or more flags may be raised and flown. 

verb
  • Exit a country momentarily and reenter. Usually this is done to satisfy immigration requirements. 

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