exoderm vs hangnail

exoderm

noun
  • An outer layer of skin. 

  • The outermost layer of cells in a developing embryo. 

hangnail

noun
  • A loose, narrow strip of nail tissue protruding from the side edge and anchored near the base of a fingernail or toenail. 

  • A pointed upper corner of the toenail (often created by improperly trimming by rounding the corner) that, as the nail grows, presses into the flesh or protrudes so that it may catch (“hang”) on stockings or shoes. 

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