plimsoll vs sports shoe

plimsoll

noun
  • A rubber-soled lace-up canvas shoe for sports or onboard ships; a precursor of trainers. 

  • The plimsoll symbol ⦵ (or o) that is used as a superscript in the notation of thermodynamics to indicate an arbitrarily chosen non-zero reference point. 

sports shoe

noun
  • protective covering for the foot primarily designed for sports or other forms of physical exercise 

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