derm vs exoderm

derm

noun
  • The integument of animal; the skin. 

  • Synonym of dermis. 

  • Guts, entrails. 

exoderm

noun
  • An outer layer of skin. 

  • The outermost layer of cells in a developing embryo. 

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