bottleneck vs congestion

bottleneck

noun
  • In traffic, any narrowing of the road, especially resulting in a delay. 

  • The part of a process that is too slow or cumbersome. 

  • The narrow portion that forms the pouring spout of a bottle; the neck of a bottle. 

verb
  • To slow by causing a bottleneck. 

  • To form a bottleneck. 

congestion

noun
  • An excess of traffic; usually not a complete standstill of traffic, so usually not synonymous with traffic jam. 

  • An excess of mucus or fluid in the respiratory system; congestion of the lungs, or nasal congestion. 

  • edema, water retention, swelling, enlargement of a body part because of fluid retention in tissues and vessels 

  • An accumulation or buildup, the act of gathering into a heap or mass. 

  • Blocking up of the capillary and other blood vessels, etc., in any locality or organ (often producing other morbid symptoms); local hypermic, active or passive 

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