infantry vs serviceperson

infantry

noun
  • The part of an army consisting of infantry soldiers, especially opposed to mounted and technical troops 

  • A regiment of infantry 

  • Soldiers who fight on foot (on land), as opposed to cavalry and other mounted units, regardless of external transport (e.g. airborne). 

serviceperson

noun
  • A servicemember; a serviceman or servicewoman. 

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