brick wall vs crenellation

brick wall

noun
  • 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. 

  • An obstacle. 

verb
  • To halt or limit abruptly. 

  • To build a brick wall around. 

  • To be uncooperative and unresponsive. 

  • To filter using a brick wall filter. 

crenellation

noun
  • A pattern along the top of a parapet (fortified wall), most often in the form of multiple, regular, rectangular spaces in the top of the wall, through which arrows or other weaponry may be shot, especially as used in medieval European architecture. 

  • The act of crenellating; adding a top row that looks like the top of a medieval castle. 

  • Any of a series of notches with fancied resemblance to such battlements, as for example around the bezel of a flashlight. 

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