blowhole vs outfall

blowhole

noun
  • A vent for the escape of steam or other gas. 

  • A top-facing opening to a cavity in the ground very near an ocean's shore, leading to a marine cave from which wave water or bursts of air are expelled. 

  • The spiracle, on the top of the head, through which cetaceans breathe. 

  • A vertical opening in the top of a computer case that lets hot air (primarily from the CPU heat sink) escape quickly. 

  • An unintended cavity filled with air in a casting product. 

verb
  • To fill or be filled with air in an unintended cavity. 

outfall

noun
  • The point or place of discharge of a river, drain, culvert, sewer, etc.; mouth; embouchure. 

  • A quarrel; a falling out. 

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