serration vs sprocket

serration

noun
  • A set of teeth or notches. 

  • One of the teeth in a serrated or serrate edge. 

  • The state of being serrated. 

sprocket

noun
  • The tooth of such a wheel. 

  • A toothed wheel that enmeshes with a chain or other perforated band. 

  • A placeholder name for an unnamed, unspecified, or hypothetical manufactured good or product. 

  • A flared extension at the base of a sloped roof. 

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