shallow vs skin-deep

shallow

adj
  • Having little depth; significantly less deep than wide. 

  • Not steep; close to horizontal. 

  • Not far forward, close to the net. 

  • Not intellectually deep; not penetrating deeply; simple; not wise or knowing. 

  • Concerned mainly with superficial matters. 

  • Extending not far downward. 

  • Lacking interest or substance. 

noun
  • A costermonger's barrow. 

  • A shallow portion of an otherwise deep body of water. 

  • A fish, the rudd. 

verb
  • To make or become less deep. 

skin-deep

adj
  • Shallow, superficial. 

How often have the words shallow and skin-deep occurred in a corpus of books? (source: Google Ngram Viewer )