leatherneck vs thalassoid

leatherneck

noun

  • Specifically, a marine. 

  • A soldier. 

thalassoid

noun

  • Any small lunar "sea" 

  • Any moth of the genus Thalassodes 

adj

  • Synonym of marine 

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