tug vs water wheel

tug

noun
  • An iron hook of a hoisting tub, to which a tackle is affixed. 

  • A dog toy consisting of a rope, often with a knot in it. 

  • A trace, or drawing strap, of a harness. 

  • A tugboat. 

  • A sudden powerful pull. 

  • An act of male masturbation. 

verb
  • To masturbate. 

  • To tow by tugboat. 

  • To pull or drag with great effort. 

  • To pull hard repeatedly. 

water wheel

noun
  • A wheel with buckets used to raise water. 

  • A wheel, propelled by running or falling water, used to power machinery. 

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