flagpole vs undergang

flagpole

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

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

undergang

verb
  • To undergo; pass through; endure. 

noun
  • A passage beneath any obstruction, e.g. a roadway tunnel beneath a railway, etc. 

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