semi vs wheels

semi

noun
  • A semi-trailer; a tractor-trailer; an eighteen-wheeler; an artic. 

  • A semifinal. 

  • A semi-detached house. 

  • A partial erection of the penis. 

wheels

noun
  • An automobile or other vehicle; a set of wheels. 

  • Well-developed thigh muscles. 

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