waterfall vs weir

waterfall

noun
  • A flow of water over the edge of a cliff. 

  • A waterfall-like outpouring of liquid, smoke, etc. 

  • Waterfall model 

  • The action of drinking from a vessel without touching it with the lips, considered more sanitary for a shared vessel. 

verb
  • To drink (something) from a container by pouring it from a height so as not to touch one's lips to the rim. 

  • To fall like a waterfall. 

  • Synonym of recycle 

weir

noun
  • An adjustable dam placed across a river to regulate the flow of water downstream. 

  • A fence placed across a river to catch fish. 

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