cuirass vs plastron

cuirass

noun
  • The breastplate taken by itself. 

  • A piece of defensive armor, covering the body from the neck to the girdle. 

verb
  • To cover with defensive armor; to armor-plate. 

plastron

noun
  • A breastplate. 

  • A half-jacket worn under the jacket for padding or for safety. 

  • The nearly flat part of the shell structure of a tortoise or other animal, similar in composition to the carapace. 

  • A film of air trapped by specialized hairs against the body of an aquatic insect, and which acts as an external gill. 

  • An ornamental front panel on a woman's bodice. 

  • A man's shirt-bosom. 

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