dandruff vs epidermis

dandruff

noun
  • scaly white dead skin flakes from the human scalp; Pityriasis capitis 

verb
  • To fall or cover with white flakes, like dandruff. 

epidermis

noun
  • The outer, protective layer of the skin of vertebrates, covering the dermis 

  • The similar outer layer of cells in invertebrates and plants 

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