boxing vs sparring

boxing

noun
  • Casing. 

  • Automatic conversion of value types to objects by wrapping them within a heap-allocated reference type. 

  • Material used for making boxes or casing. 

  • A sport where two opponents punch each other with gloved fists to head and torso; the object being to score more points by the end of the match or by knockout, or technical knockout. 

sparring

noun
  • The act of one who spars. 

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