bottleneck vs obstruction

bottleneck

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

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

  • 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. 

obstruction

noun
  • Something which obstructs or impedes, either intentionally or unintentionally 

  • The act of obstructing, or state of being obstructed. 

  • The condition of having the natural powers obstructed in their usual course; the arrest of the vital functions; death. 

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