admiral vs navarch

admiral

noun
  • A naval officer of the highest rank; the commander of a country's naval forces. 

  • The ship which carries the admiral, the flagship; also, the most considerable ship of a fleet. 

  • A naval officer of high rank, immediately below Admiral of the Fleet; the commander of a fleet or squadron. 

  • A flag officer in the United States Navy or Coast Guard of a grade superior to vice admiral and junior to admiral of the fleet (when that grade is used). An admiral is equal in grade or rank to a four-star general. 

  • Any of various nymphalid butterflies of the genera Kaniska, Limenitis and Vanessa, especially a red admiral or white admiral. 

navarch

noun
  • The commander of a fleet. 

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